[syzbot] KASAN: use-after-free Read in disk_part_iter_next (2)

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syzbot

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Mar 14, 2021, 7:08:16 AM3/14/21
to ax...@kernel.dk, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 280d542f Merge tag 'drm-fixes-2021-03-05' of git://anongit..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15ade5aed00000
kernel config: https://syzkaller.appspot.com/x/.config?x=952047a9dbff6a6a
dashboard link: https://syzkaller.appspot.com/bug?extid=8fede7e30c7cee0de139

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8fede7...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in bdev_nr_sectors include/linux/genhd.h:266 [inline]
BUG: KASAN: use-after-free in disk_part_iter_next+0x49d/0x530 block/genhd.c:207
Read of size 8 at addr ffff88804b0022e8 by task systemd-udevd/9804

CPU: 1 PID: 9804 Comm: systemd-udevd Not tainted 5.12.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0xfa/0x151 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2c6 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
bdev_nr_sectors include/linux/genhd.h:266 [inline]
disk_part_iter_next+0x49d/0x530 block/genhd.c:207
blk_drop_partitions+0x10a/0x180 block/partitions/core.c:543
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1237
__loop_clr_fd+0x7c7/0xff0 drivers/block/loop.c:1271
lo_release+0x1ac/0x1f0 drivers/block/loop.c:1923
__blkdev_put+0x54e/0x800 fs/block_dev.c:1579
blkdev_put+0x92/0x580 fs/block_dev.c:1632
blkdev_close+0x8c/0xb0 fs/block_dev.c:1640
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f8141652270
Code: 73 01 c3 48 8b 0d 38 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c1 20 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ee fb ff ff 48 89 04 24
RSP: 002b:00007ffe05d67588 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007f8141652270
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 00007f814250c710 R08: 000055e767969790 R09: 000055e767968300
R10: 00007f814250c8c0 R11: 0000000000000246 R12: 0000000000000000
R13: 000055e767979eb0 R14: 0000000000000003 R15: 000000000000000e

Allocated by task 9582:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:427 [inline]
__kasan_slab_alloc+0x73/0x90 mm/kasan/common.c:460
kasan_slab_alloc include/linux/kasan.h:223 [inline]
slab_post_alloc_hook mm/slab.h:516 [inline]
slab_alloc mm/slab.c:3325 [inline]
kmem_cache_alloc+0x1c3/0x4f0 mm/slab.c:3502
bdev_alloc_inode+0x18/0x80 fs/block_dev.c:786
alloc_inode+0x61/0x230 fs/inode.c:234
new_inode_pseudo fs/inode.c:928 [inline]
new_inode+0x27/0x2f0 fs/inode.c:957
bdev_alloc+0x20/0x2f0 fs/block_dev.c:876
add_partition+0x1ab/0x8a0 block/partitions/core.c:348
bdev_add_partition+0xb6/0x130 block/partitions/core.c:451
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1658
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 8676:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
____kasan_slab_free mm/kasan/common.c:360 [inline]
____kasan_slab_free mm/kasan/common.c:325 [inline]
__kasan_slab_free+0xc7/0x100 mm/kasan/common.c:367
kasan_slab_free include/linux/kasan.h:199 [inline]
__cache_free mm/slab.c:3440 [inline]
kmem_cache_free+0x6f/0x1d0 mm/slab.c:3733
i_callback+0x3f/0x70 fs/inode.c:223
rcu_do_batch kernel/rcu/tree.c:2559 [inline]
rcu_core+0x722/0x1280 kernel/rcu/tree.c:2794
__do_softirq+0x29b/0x9f6 kernel/softirq.c:345

Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xa4/0xd0 mm/kasan/generic.c:345
__call_rcu kernel/rcu/tree.c:3039 [inline]
call_rcu+0xb1/0x700 kernel/rcu/tree.c:3114
destroy_inode+0x129/0x1b0 fs/inode.c:289
iput_final fs/inode.c:1654 [inline]
iput.part.0+0x57e/0x810 fs/inode.c:1680
iput+0x58/0x70 fs/inode.c:1670
disk_part_iter_exit block/genhd.c:236 [inline]
disk_part_iter_next+0x9a/0x530 block/genhd.c:203
blk_drop_partitions+0x10a/0x180 block/partitions/core.c:543
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1237
loop_reread_partitions+0x29/0x50 drivers/block/loop.c:655
loop_set_status+0x704/0x1050 drivers/block/loop.c:1418
loop_set_status64 drivers/block/loop.c:1538 [inline]
lo_ioctl+0x4ca/0x1620 drivers/block/loop.c:1706
blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:583
block_ioctl+0xf9/0x140 fs/block_dev.c:1658
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88804b0022c0
which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
2792-byte region [ffff88804b0022c0, ffff88804b002da8)
The buggy address belongs to the page:
page:00000000708f9251 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88804b002fff pfn:0x4b002
flags: 0x4fff00000000200(slab)
raw: 04fff00000000200 ffffea00010ecd48 ffffea00012c2fc8 ffff888010b95700
raw: ffff88804b002fff ffff88804b0022c0 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88804b002180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88804b002200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88804b002280: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
^
ffff88804b002300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88804b002380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

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syzbot

unread,
Mar 20, 2021, 4:53:23 PM3/20/21
to ax...@kernel.dk, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com
syzbot has found a reproducer for the following issue on:

HEAD commit: 1c273e10 Merge tag 'zonefs-5.12-rc4' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16889906d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=6abda3336c698a07
dashboard link: https://syzkaller.appspot.com/bug?extid=8fede7e30c7cee0de139
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13dfe8bed00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=155a117cd00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8fede7...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in bdev_nr_sectors include/linux/genhd.h:266 [inline]
BUG: KASAN: use-after-free in disk_part_iter_next+0x49d/0x530 block/genhd.c:206
Read of size 8 at addr ffff88803268d0a8 by task syz-executor193/10255

CPU: 0 PID: 10255 Comm: syz-executor193 Not tainted 5.12.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
bdev_nr_sectors include/linux/genhd.h:266 [inline]
disk_part_iter_next+0x49d/0x530 block/genhd.c:206
partition_overlaps+0x96/0x200 block/partitions/core.c:425
bdev_add_partition+0x66/0x130 block/partitions/core.c:444
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x445739
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffca5947308 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000445739
RDX: 0000000020000240 RSI: 0000000000001269 RDI: 0000000000000003
RBP: 00007ffca5947380 R08: 000000000000ece4 R09: 000000000000ece4
R10: 0023706f6f6c2f76 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffca5947370 R14: 00007ffca5947360 R15: 00007ffca594732c

Allocated by task 10192:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:427 [inline]
__kasan_slab_alloc+0x75/0x90 mm/kasan/common.c:460
kasan_slab_alloc include/linux/kasan.h:223 [inline]
slab_post_alloc_hook mm/slab.h:516 [inline]
slab_alloc_node mm/slub.c:2907 [inline]
slab_alloc mm/slub.c:2915 [inline]
kmem_cache_alloc+0x155/0x370 mm/slub.c:2920
bdev_alloc_inode+0x18/0x80 fs/block_dev.c:795
alloc_inode+0x61/0x230 fs/inode.c:234
new_inode_pseudo fs/inode.c:928 [inline]
new_inode+0x27/0x2f0 fs/inode.c:957
bdev_alloc+0x20/0x2f0 fs/block_dev.c:885
add_partition+0x1ab/0x880 block/partitions/core.c:346
bdev_add_partition+0xb6/0x130 block/partitions/core.c:449
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 0:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
____kasan_slab_free mm/kasan/common.c:360 [inline]
____kasan_slab_free mm/kasan/common.c:325 [inline]
__kasan_slab_free+0xf5/0x130 mm/kasan/common.c:367
kasan_slab_free include/linux/kasan.h:199 [inline]
slab_free_hook mm/slub.c:1562 [inline]
slab_free_freelist_hook+0x92/0x210 mm/slub.c:1600
slab_free mm/slub.c:3161 [inline]
kmem_cache_free+0x8a/0x740 mm/slub.c:3177
i_callback+0x3f/0x70 fs/inode.c:223
rcu_do_batch kernel/rcu/tree.c:2559 [inline]
rcu_core+0x74a/0x12f0 kernel/rcu/tree.c:2794
__do_softirq+0x29b/0x9f6 kernel/softirq.c:345

Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
__call_rcu kernel/rcu/tree.c:3039 [inline]
call_rcu+0xb1/0x740 kernel/rcu/tree.c:3114
destroy_inode+0x129/0x1b0 fs/inode.c:289
iput_final fs/inode.c:1654 [inline]
iput.part.0+0x57e/0x810 fs/inode.c:1680
iput+0x58/0x70 fs/inode.c:1670
disk_part_iter_exit block/genhd.c:235 [inline]
disk_part_iter_next+0x9a/0x530 block/genhd.c:202
blk_drop_partitions+0x10a/0x180 block/partitions/core.c:541
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1246
__loop_clr_fd+0x7c7/0xff0 drivers/block/loop.c:1271
lo_release+0x1ac/0x1f0 drivers/block/loop.c:1923
__blkdev_put+0x54e/0x800 fs/block_dev.c:1588
blkdev_put+0x92/0x580 fs/block_dev.c:1641
blkdev_close+0x8c/0xb0 fs/block_dev.c:1649
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xae

Second to last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
__call_rcu kernel/rcu/tree.c:3039 [inline]
call_rcu+0xb1/0x740 kernel/rcu/tree.c:3114
destroy_inode+0x129/0x1b0 fs/inode.c:289
iput_final fs/inode.c:1654 [inline]
iput.part.0+0x57e/0x810 fs/inode.c:1680
iput+0x58/0x70 fs/inode.c:1670
disk_part_iter_exit block/genhd.c:235 [inline]
disk_part_iter_next+0x9a/0x530 block/genhd.c:202
blk_drop_partitions+0x10a/0x180 block/partitions/core.c:541
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1246
__blkdev_get+0x86c/0xa30 fs/block_dev.c:1350
blkdev_get_by_dev fs/block_dev.c:1454 [inline]
blkdev_get_by_dev+0x26c/0x600 fs/block_dev.c:1422
blkdev_reread_part block/ioctl.c:100 [inline]
blkdev_common_ioctl+0x137e/0x17e0 block/ioctl.c:508
blkdev_ioctl+0x1ef/0x6d0 block/ioctl.c:577
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88803268d080
which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
2792-byte region [ffff88803268d080, ffff88803268db68)
The buggy address belongs to the page:
page:ffffea0000c9a200 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x32688
head:ffffea0000c9a200 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 ffffea0005110a00 0000000200000002 ffff8880109bdb40
raw: 0000000000000000 00000000800b000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88803268cf80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
ffff88803268d000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88803268d080: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88803268d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88803268d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

syzbot

unread,
Mar 21, 2021, 8:40:05 AM3/21/21
to ax...@kernel.dk, h...@lst.de, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, t...@kernel.org
syzbot has bisected this issue to:

commit a33df75c6328bf40078b35f2040d8e54d574c357
Author: Christoph Hellwig <h...@lst.de>
Date: Sun Jan 24 10:02:41 2021 +0000

block: use an xarray for disk->part_tbl

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17989906d00000
start commit: 1c273e10 Merge tag 'zonefs-5.12-rc4' of git://git.kernel.o..
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=14589906d00000
console output: https://syzkaller.appspot.com/x/log.txt?x=10589906d00000
Reported-by: syzbot+8fede7...@syzkaller.appspotmail.com
Fixes: a33df75c6328 ("block: use an xarray for disk->part_tbl")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Bart Van Assche

unread,
Mar 21, 2021, 5:26:11 PM3/21/21
to syzbot, ax...@kernel.dk, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On 3/14/21 4:08 AM, syzbot wrote:
> syzbot found the following issue on:
>
> HEAD commit: 280d542f Merge tag 'drm-fixes-2021-03-05' of git://anongit..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15ade5aed00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=952047a9dbff6a6a
> dashboard link: https://syzkaller.appspot.com/bug?extid=8fede7e30c7cee0de139

#syz test: https://github.com/bvanassche/linux a5f35387ebdc

syzbot

unread,
Mar 21, 2021, 5:39:10 PM3/21/21
to ax...@kernel.dk, bvana...@acm.org, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in disk_part_iter_next

==================================================================
BUG: KASAN: use-after-free in bdev_nr_sectors include/linux/genhd.h:266 [inline]
BUG: KASAN: use-after-free in disk_part_iter_next+0x49d/0x530 block/genhd.c:206
Read of size 8 at addr ffff88801626b9a8 by task syz-executor.0/10146

CPU: 0 PID: 10146 Comm: syz-executor.0 Not tainted 5.12.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
bdev_nr_sectors include/linux/genhd.h:266 [inline]
disk_part_iter_next+0x49d/0x530 block/genhd.c:206
blk_drop_partitions+0x10a/0x180 block/partitions/core.c:543
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1246
__loop_clr_fd+0x7c7/0xff0 drivers/block/loop.c:1271
lo_release+0x1ac/0x1f0 drivers/block/loop.c:1923
__blkdev_put+0x54e/0x800 fs/block_dev.c:1588
blkdev_put+0x92/0x580 fs/block_dev.c:1641
blkdev_close+0x8c/0xb0 fs/block_dev.c:1649
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x41926b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007ffc4fc09520 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 000000000041926b
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000001b30620070
R10: 0000000000000000 R11: 0000000000000293 R12: 000000000056c9e0
R13: 000000000056c9e0 R14: 000000000056bf60 R15: 0000000000013222

Allocated by task 10160:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:427 [inline]
__kasan_slab_alloc+0x75/0x90 mm/kasan/common.c:460
kasan_slab_alloc include/linux/kasan.h:223 [inline]
slab_post_alloc_hook mm/slab.h:516 [inline]
slab_alloc_node mm/slub.c:2907 [inline]
slab_alloc mm/slub.c:2915 [inline]
kmem_cache_alloc+0x155/0x370 mm/slub.c:2920
bdev_alloc_inode+0x18/0x80 fs/block_dev.c:795
alloc_inode+0x61/0x230 fs/inode.c:234
new_inode_pseudo fs/inode.c:928 [inline]
new_inode+0x27/0x2f0 fs/inode.c:957
bdev_alloc+0x20/0x2f0 fs/block_dev.c:885
add_partition+0x1ab/0x880 block/partitions/core.c:348
bdev_add_partition+0xb6/0x130 block/partitions/core.c:451
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 13:
blk_drop_partitions+0x10a/0x180 block/partitions/core.c:543
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1246
loop_reread_partitions+0x29/0x50 drivers/block/loop.c:655
loop_set_status+0x704/0x1050 drivers/block/loop.c:1418
loop_set_status64 drivers/block/loop.c:1538 [inline]
lo_ioctl+0x4ca/0x1620 drivers/block/loop.c:1706
blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:583
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88801626b980
which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
2792-byte region [ffff88801626b980, ffff88801626c468)
The buggy address belongs to the page:
page:ffffea0000589a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16268
head:ffffea0000589a00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff8880101bdb40
raw: 0000000000000000 00000000800b000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88801626b880: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
ffff88801626b900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801626b980: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88801626ba00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88801626ba80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: a5f35387 block: Fix a race between reading and freeing par..
git tree: https://github.com/bvanassche/linux
console output: https://syzkaller.appspot.com/x/log.txt?x=13534e62d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b5da36c3359b30d1
dashboard link: https://syzkaller.appspot.com/bug?extid=8fede7e30c7cee0de139
compiler:

Ming Lei

unread,
Mar 21, 2021, 10:35:55 PM3/21/21
to Bart Van Assche, syzbot, Jens Axboe, linux-block, Linux Kernel Mailing List, syzkall...@googlegroups.com
It should be the same issue which was addressed by

aebf5db91705 block: fix use-after-free in disk_part_iter_next

but converting to xarray introduced the issue again.

--
Ming Lei

Hillf Danton

unread,
Mar 21, 2021, 11:53:34 PM3/21/21
to syzbot, ax...@kernel.dk, bvana...@acm.org, Hillf Danton, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com
On Sun, 21 Mar 2021 14:39:09
> Hello,
>
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> KASAN: use-after-free Read in disk_part_iter_next
>
> ==================================================================
> BUG: KASAN: use-after-free in bdev_nr_sectors include/linux/genhd.h:266 [inline]
> BUG: KASAN: use-after-free in disk_part_iter_next+0x49d/0x530 block/genhd.c:206
> Read of size 8 at addr ffff88801626b9a8 by task syz-executor.0/10146
>
> CPU: 0 PID: 10146 Comm: syz-executor.0 Not tainted 5.12.0-rc3-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
> __dump_stack lib/dump_stack.c:79 [inline]
> dump_stack+0x141/0x1d7 lib/dump_stack.c:120
> print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
> __kasan_report mm/kasan/report.c:399 [inline]
> kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
> bdev_nr_sectors include/linux/genhd.h:266 [inline]
> disk_part_iter_next+0x49d/0x530 block/genhd.c:206
> blk_drop_partitions+0x10a/0x180 block/partitions/core.c:543

This is the victim of the race between fput and ioctl.
Fix the race in walking partition table by adding a mutex lock to genhd.

--- x/block/partitions/core.c
+++ y/block/partitions/core.c
@@ -530,6 +530,7 @@ int blk_drop_partitions(struct block_dev
{
struct disk_part_iter piter;
struct block_device *part;
+ struct mutex *ptl;

if (bdev->bd_part_count)
return -EBUSY;
@@ -538,9 +539,14 @@ int blk_drop_partitions(struct block_dev
invalidate_bdev(bdev);

disk_part_iter_init(&piter, bdev->bd_disk, DISK_PITER_INCL_EMPTY);
+ ptl = &bdev->bd_disk->part_tbl_mutex;
+ mutex_lock(ptl);
+
while ((part = disk_part_iter_next(&piter)))
delete_partition(part);
+
disk_part_iter_exit(&piter);
+ mutex_unlock(ptl);

return 0;
}
--- x/include/linux/genhd.h
+++ y/include/linux/genhd.h
@@ -143,6 +143,7 @@ struct gendisk {
unsigned short event_flags; /* flags related to event processing */

struct xarray part_tbl;
+ struct mutex part_tbl_mutex;
struct block_device *part0;

const struct block_device_operations *fops;
--- x/block/genhd.c
+++ y/block/genhd.c
@@ -1379,6 +1379,7 @@ struct gendisk *__alloc_disk_node(int mi
goto out_free_disk;

disk->node_id = node_id;
+ mutex_init(&disk->part_tbl_mutex);
xa_init(&disk->part_tbl);
if (xa_insert(&disk->part_tbl, 0, disk->part0, GFP_KERNEL))
goto out_destroy_part_tbl;

Bart Van Assche

unread,
Mar 22, 2021, 12:15:59 AM3/22/21
to Ming Lei, syzbot, Jens Axboe, linux-block, Linux Kernel Mailing List, syzkall...@googlegroups.com, Hillf Danton
Hi Ming,

Since that patch does not re-apply cleanly, do you want to convert that
patch to the latest kernel version or do you perhaps expect me to do that?

Thanks,

Bart.

Christoph Hellwig

unread,
Mar 22, 2021, 3:18:05 AM3/22/21
to syzbot, ax...@kernel.dk, h...@lst.de, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, t...@kernel.org
I've been running the reproducer on a KASAN enable VM for about
15 minutes now, but haven't been able to reproduce it.

Is there a way to inject this proposed fix into the syzbot queue?

diff --git a/block/partitions/core.c b/block/partitions/core.c
index 1a7558917c47d6..f5d5872b89d57e 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -288,15 +288,12 @@ struct device_type part_type = {
void delete_partition(struct block_device *part)
{
xa_erase(&part->bd_disk->part_tbl, part->bd_partno);
- kobject_put(part->bd_holder_dir);
- device_del(&part->bd_device);
-
- /*
- * Remove the block device from the inode hash, so that it cannot be
- * looked up any more even when openers still hold references.
- */
remove_inode_hash(part->bd_inode);

+ synchronize_rcu();
+
+ kobject_put(part->bd_holder_dir);
+ device_del(&part->bd_device);
put_device(&part->bd_device);
}

syzbot

unread,
Mar 22, 2021, 4:01:05 AM3/22/21
to ax...@kernel.dk, dvy...@google.com, h...@lst.de, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, t...@kernel.org
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in disk_part_iter_next

==================================================================
BUG: KASAN: use-after-free in bdev_nr_sectors include/linux/genhd.h:266 [inline]
BUG: KASAN: use-after-free in disk_part_iter_next+0x49d/0x530 block/genhd.c:206
Read of size 8 at addr ffff88814403d0a8 by task syz-executor.0/10269

CPU: 1 PID: 10269 Comm: syz-executor.0 Not tainted 5.12.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
bdev_nr_sectors include/linux/genhd.h:266 [inline]
disk_part_iter_next+0x49d/0x530 block/genhd.c:206
partition_overlaps+0x96/0x200 block/partitions/core.c:422
bdev_add_partition+0x66/0x130 block/partitions/core.c:441
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f65eb831188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000466459
RDX: 0000000020000240 RSI: 0000000000001269 RDI: 0000000000000003
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007ffc7d37ce9f R14: 00007f65eb831300 R15: 0000000000022000

Allocated by task 10226:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:427 [inline]
__kasan_slab_alloc+0x75/0x90 mm/kasan/common.c:460
kasan_slab_alloc include/linux/kasan.h:223 [inline]
slab_post_alloc_hook mm/slab.h:516 [inline]
slab_alloc_node mm/slub.c:2907 [inline]
slab_alloc mm/slub.c:2915 [inline]
kmem_cache_alloc+0x155/0x370 mm/slub.c:2920
bdev_alloc_inode+0x18/0x80 fs/block_dev.c:795
alloc_inode+0x61/0x230 fs/inode.c:234
new_inode_pseudo fs/inode.c:928 [inline]
new_inode+0x27/0x2f0 fs/inode.c:957
bdev_alloc+0x20/0x2f0 fs/block_dev.c:885
add_partition+0x1ab/0x880 block/partitions/core.c:343
bdev_add_partition+0xb6/0x130 block/partitions/core.c:446
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 10255:
blk_drop_partitions+0x10a/0x180 block/partitions/core.c:538
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1246
loop_reread_partitions+0x29/0x50 drivers/block/loop.c:655
loop_set_status+0x704/0x1050 drivers/block/loop.c:1418
loop_set_status64 drivers/block/loop.c:1538 [inline]
lo_ioctl+0x4ca/0x1620 drivers/block/loop.c:1706
blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:583
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88814403d080
which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
2792-byte region [ffff88814403d080, ffff88814403db68)
The buggy address belongs to the page:
page:ffffea0005100e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x144038
head:ffffea0005100e00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head)
raw: 057ff00000010200 dead000000000100 dead000000000122 ffff8880101bdb40
raw: 0000000000000000 00000000000b000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88814403cf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
ffff88814403d000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88814403d080: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88814403d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88814403d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: 0d02ec6b Linux 5.12-rc4
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=127b4506d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=4b6433fa3370faed
patch: https://syzkaller.appspot.com/x/patch.diff?x=14d738bed00000

Ming Lei

unread,
Mar 22, 2021, 4:51:45 AM3/22/21
to syzbot, Jens Axboe, linux-block, Linux Kernel Mailing List, syzkall...@googlegroups.com
On Sun, Mar 14, 2021 at 7:10 PM syzbot
<syzbot+8fede7...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 280d542f Merge tag 'drm-fixes-2021-03-05' of git://anongit..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15ade5aed00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=952047a9dbff6a6a
> dashboard link: https://syzkaller.appspot.com/bug?extid=8fede7e30c7cee0de139
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+8fede7...@syzkaller.appspotmail.com

#syz test: https://github.com/ming1/linux.git v5.12-block-test

syzbot

unread,
Mar 22, 2021, 6:09:06 AM3/22/21
to ax...@kernel.dk, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, tom.l...@gmail.com
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in bdgrab

==================================================================
BUG: KASAN: use-after-free in bdgrab+0x4c/0x50 fs/block_dev.c:938
Read of size 8 at addr ffff88814442d0a8 by task syz-executor.4/10282

CPU: 1 PID: 10282 Comm: syz-executor.4 Not tainted 5.12.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
bdgrab+0x4c/0x50 fs/block_dev.c:938
disk_part_iter_next+0x1ce/0x530 block/genhd.c:206
partition_overlaps+0x96/0x200 block/partitions/core.c:425
bdev_add_partition+0x66/0x130 block/partitions/core.c:444
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x466459
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f8adaa92188 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000466459
RDX: 0000000020000240 RSI: 0000000000001269 RDI: 0000000000000003
RBP: 00000000004bf9fb R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007ffef77424cf R14: 00007f8adaa92300 R15: 0000000000022000

Allocated by task 10147:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:427 [inline]
__kasan_slab_alloc+0x75/0x90 mm/kasan/common.c:460
kasan_slab_alloc include/linux/kasan.h:223 [inline]
slab_post_alloc_hook mm/slab.h:516 [inline]
slab_alloc_node mm/slub.c:2907 [inline]
slab_alloc mm/slub.c:2915 [inline]
kmem_cache_alloc+0x155/0x370 mm/slub.c:2920
bdev_alloc_inode+0x18/0x80 fs/block_dev.c:795
alloc_inode+0x61/0x230 fs/inode.c:234
new_inode_pseudo fs/inode.c:928 [inline]
new_inode+0x27/0x2f0 fs/inode.c:957
bdev_alloc+0x20/0x2f0 fs/block_dev.c:885
add_partition+0x1ab/0x880 block/partitions/core.c:346
bdev_add_partition+0xb6/0x130 block/partitions/core.c:449
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 346:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
____kasan_slab_free mm/kasan/common.c:360 [inline]
____kasan_slab_free mm/kasan/common.c:325 [inline]
__kasan_slab_free+0xf5/0x130 mm/kasan/common.c:367
kasan_slab_free include/linux/kasan.h:199 [inline]
slab_free_hook mm/slub.c:1562 [inline]
slab_free_freelist_hook+0x92/0x210 mm/slub.c:1600
slab_free mm/slub.c:3161 [inline]
kmem_cache_free+0x8a/0x740 mm/slub.c:3177
i_callback+0x3f/0x70 fs/inode.c:223
rcu_do_batch kernel/rcu/tree.c:2559 [inline]
rcu_core+0x74a/0x12f0 kernel/rcu/tree.c:2794
__do_softirq+0x29b/0x9f6 kernel/softirq.c:345

Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
__call_rcu kernel/rcu/tree.c:3039 [inline]
call_rcu+0xb1/0x740 kernel/rcu/tree.c:3114
destroy_inode+0x129/0x1b0 fs/inode.c:289
iput_final fs/inode.c:1654 [inline]
iput.part.0+0x57e/0x810 fs/inode.c:1680
iput+0x58/0x70 fs/inode.c:1670
disk_part_iter_exit block/genhd.c:236 [inline]
disk_part_iter_next+0x9b/0x530 block/genhd.c:202
blk_drop_partitions+0x10a/0x180 block/partitions/core.c:541
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1246
loop_reread_partitions+0x29/0x50 drivers/block/loop.c:655
loop_set_status+0x704/0x1050 drivers/block/loop.c:1418
loop_set_status64 drivers/block/loop.c:1538 [inline]
lo_ioctl+0x4ca/0x1620 drivers/block/loop.c:1706
blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:583
block_ioctl+0xf9/0x140 fs/block_dev.c:1667
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88814442d080
which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
2792-byte region [ffff88814442d080, ffff88814442db68)
The buggy address belongs to the page:
page:ffffea0005110a00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x144428
head:ffffea0005110a00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head)
raw: 057ff00000010200 dead000000000100 dead000000000122 ffff8880101bdb40
raw: 0000000000000000 00000000800b000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88814442cf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
ffff88814442d000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88814442d080: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88814442d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88814442d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: ee788c30 block: fix use-after-free in disk_part_iter_next
git tree: https://github.com/ming1/linux.git v5.12-block-test
console output: https://syzkaller.appspot.com/x/log.txt?x=15f526d6d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b5da36c3359b30d1

Bart Van Assche

unread,
Mar 22, 2021, 6:21:24 PM3/22/21
to Christoph Hellwig, syzbot, ax...@kernel.dk, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, t...@kernel.org
Hi Christoph,

disk_part_iter_next() calls bdgrab() before returning a pointer to a
certain partition. 'part' is only freed if its reference count drops to
zero. The function that frees the partition information,
bdev_free_inode(), is invoked via call_rcu(). bdgrab() fails if the
refcount of a partition is zero. Does that mean that it is not necessary
to call synchronize_rcu() between xa_erase() and put_device()?

Thanks,

Bart.

Christoph Hellwig

unread,
Mar 24, 2021, 5:49:49 AM3/24/21
to syzbot, ax...@kernel.dk, h...@lst.de, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, t...@kernel.org
#syz test: git://git.infradead.org/users/hch/block.git part-iter-fix
---end quoted text---

syzbot

unread,
Mar 24, 2021, 6:01:07 AM3/24/21
to ax...@kernel.dk, h...@lst.de, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, t...@kernel.org
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in bdgrab

==================================================================
BUG: KASAN: use-after-free in bdgrab+0x4c/0x50 fs/block_dev.c:929
Read of size 8 at addr ffff88801639a2a8 by task syz-executor.0/10133

CPU: 1 PID: 10133 Comm: syz-executor.0 Not tainted 5.12.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
bdgrab+0x4c/0x50 fs/block_dev.c:929
first_partition+0xfa/0x230 block/partitions/core.c:538
blk_drop_partitions+0xb5/0xf0 block/partitions/core.c:555
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1237
__loop_clr_fd+0x7c7/0xff0 drivers/block/loop.c:1271
lo_release+0x1ac/0x1f0 drivers/block/loop.c:1923
__blkdev_put+0x54e/0x800 fs/block_dev.c:1579
blkdev_put+0x92/0x580 fs/block_dev.c:1632
blkdev_close+0x8c/0xb0 fs/block_dev.c:1640
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x41926b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007fff13e6a990 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 000000000041926b
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000000 R09: 0000001b2fb20070
R10: 0000000000000000 R11: 0000000000000293 R12: 000000000056c9e0
R13: 000000000056c9e0 R14: 000000000056bf60 R15: 000000000001383c

Allocated by task 10136:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:427 [inline]
__kasan_slab_alloc+0x75/0x90 mm/kasan/common.c:460
kasan_slab_alloc include/linux/kasan.h:223 [inline]
slab_post_alloc_hook mm/slab.h:516 [inline]
slab_alloc_node mm/slub.c:2907 [inline]
slab_alloc mm/slub.c:2915 [inline]
kmem_cache_alloc+0x155/0x370 mm/slub.c:2920
bdev_alloc_inode+0x18/0x80 fs/block_dev.c:786
alloc_inode+0x61/0x230 fs/inode.c:234
new_inode_pseudo fs/inode.c:928 [inline]
new_inode+0x27/0x2f0 fs/inode.c:957
bdev_alloc+0x20/0x2f0 fs/block_dev.c:876
add_partition+0x1ab/0x8a0 block/partitions/core.c:348
bdev_add_partition+0xb6/0x130 block/partitions/core.c:451
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1658
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 4849:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
____kasan_slab_free mm/kasan/common.c:360 [inline]
____kasan_slab_free mm/kasan/common.c:325 [inline]
__kasan_slab_free+0xf5/0x130 mm/kasan/common.c:367
kasan_slab_free include/linux/kasan.h:199 [inline]
slab_free_hook mm/slub.c:1562 [inline]
slab_free_freelist_hook+0x92/0x210 mm/slub.c:1600
slab_free mm/slub.c:3161 [inline]
kmem_cache_free+0x8a/0x740 mm/slub.c:3177
i_callback+0x3f/0x70 fs/inode.c:223
rcu_do_batch kernel/rcu/tree.c:2559 [inline]
rcu_core+0x74a/0x12f0 kernel/rcu/tree.c:2794
__do_softirq+0x29b/0x9f6 kernel/softirq.c:345

Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
__call_rcu kernel/rcu/tree.c:3039 [inline]
call_rcu+0xb1/0x740 kernel/rcu/tree.c:3114
destroy_inode+0x129/0x1b0 fs/inode.c:289
iput_final fs/inode.c:1654 [inline]
iput.part.0+0x57e/0x810 fs/inode.c:1680
iput+0x58/0x70 fs/inode.c:1670
blk_drop_partitions+0x9d/0xf0 block/partitions/core.c:557
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1237
loop_reread_partitions+0x29/0x50 drivers/block/loop.c:655
loop_set_status+0x704/0x1050 drivers/block/loop.c:1418
loop_set_status64 drivers/block/loop.c:1538 [inline]
lo_ioctl+0x4ca/0x1620 drivers/block/loop.c:1706
blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:583
block_ioctl+0xf9/0x140 fs/block_dev.c:1658
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff88801639a280
which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
2792-byte region [ffff88801639a280, ffff88801639ad68)
The buggy address belongs to the page:
page:ffffea000058e600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x16398
head:ffffea000058e600 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff8880101bdb40
raw: 0000000000000000 00000000800b000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88801639a180: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
ffff88801639a200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801639a280: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88801639a300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88801639a380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: 7b997e8f block: simplify partition removal
git tree: git://git.infradead.org/users/hch/block.git part-iter-fix
console output: https://syzkaller.appspot.com/x/log.txt?x=14d147aed00000
kernel config: https://syzkaller.appspot.com/x/.config?x=c000f42ea85d0228

syzbot

unread,
Mar 24, 2021, 9:19:09 AM3/24/21
to h...@lst.de, syzkall...@googlegroups.com
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in bdgrab

==================================================================
BUG: KASAN: use-after-free in bdgrab+0x4c/0x50 fs/block_dev.c:929
Read of size 8 at addr ffff8881440f9728 by task systemd-udevd/10197

CPU: 0 PID: 10197 Comm: systemd-udevd Not tainted 5.12.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
bdgrab+0x4c/0x50 fs/block_dev.c:929
first_partition+0xfa/0x230 block/partitions/core.c:534
blk_drop_partitions+0xb5/0xf0 block/partitions/core.c:551
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1237
__loop_clr_fd+0x7c7/0xff0 drivers/block/loop.c:1271
lo_release+0x1ac/0x1f0 drivers/block/loop.c:1923
__blkdev_put+0x54e/0x800 fs/block_dev.c:1579
blkdev_put+0x92/0x580 fs/block_dev.c:1632
blkdev_close+0x8c/0xb0 fs/block_dev.c:1640
__fput+0x288/0x920 fs/file_table.c:280
task_work_run+0xdd/0x1a0 kernel/task_work.c:140
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
exit_to_user_mode_prepare+0x249/0x250 kernel/entry/common.c:208
__syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:301
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fb045e91270
Code: 73 01 c3 48 8b 0d 38 7d 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 59 c1 20 00 00 75 10 b8 03 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 ee fb ff ff 48 89 04 24
RSP: 002b:00007ffdf8746e68 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000007 RCX: 00007fb045e91270
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 00007fb046d4b710 R08: 000055cd21118550 R09: 000055cd21118300
R10: 00007fb046d4b8c0 R11: 0000000000000246 R12: 0000000000000000
R13: 000055cd2112a3b0 R14: 0000000000000003 R15: 000000000000000e

Allocated by task 10190:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:427 [inline]
__kasan_slab_alloc+0x75/0x90 mm/kasan/common.c:460
kasan_slab_alloc include/linux/kasan.h:223 [inline]
slab_post_alloc_hook mm/slab.h:516 [inline]
slab_alloc_node mm/slub.c:2907 [inline]
slab_alloc mm/slub.c:2915 [inline]
kmem_cache_alloc+0x155/0x370 mm/slub.c:2920
bdev_alloc_inode+0x18/0x80 fs/block_dev.c:786
alloc_inode+0x61/0x230 fs/inode.c:234
new_inode_pseudo fs/inode.c:928 [inline]
new_inode+0x27/0x2f0 fs/inode.c:957
bdev_alloc+0x20/0x2f0 fs/block_dev.c:876
add_partition+0x1ab/0x8a0 block/partitions/core.c:344
bdev_add_partition+0xb6/0x130 block/partitions/core.c:447
blkpg_do_ioctl+0x2d0/0x340 block/ioctl.c:43
blkpg_ioctl block/ioctl.c:60 [inline]
blkdev_ioctl+0x577/0x6d0 block/ioctl.c:548
block_ioctl+0xf9/0x140 fs/block_dev.c:1658
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 8780:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:357
____kasan_slab_free mm/kasan/common.c:360 [inline]
____kasan_slab_free mm/kasan/common.c:325 [inline]
__kasan_slab_free+0xf5/0x130 mm/kasan/common.c:367
kasan_slab_free include/linux/kasan.h:199 [inline]
slab_free_hook mm/slub.c:1562 [inline]
slab_free_freelist_hook+0x92/0x210 mm/slub.c:1600
slab_free mm/slub.c:3161 [inline]
kmem_cache_free+0x8a/0x740 mm/slub.c:3177
i_callback+0x3f/0x70 fs/inode.c:223
rcu_do_batch kernel/rcu/tree.c:2559 [inline]
rcu_core+0x74a/0x12f0 kernel/rcu/tree.c:2794
__do_softirq+0x29b/0x9f6 kernel/softirq.c:345

Last potentially related work creation:
kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:345
__call_rcu kernel/rcu/tree.c:3039 [inline]
call_rcu+0xb1/0x740 kernel/rcu/tree.c:3114
destroy_inode+0x129/0x1b0 fs/inode.c:289
iput_final fs/inode.c:1654 [inline]
iput.part.0+0x57e/0x810 fs/inode.c:1680
iput+0x58/0x70 fs/inode.c:1670
blk_drop_partitions+0x9d/0xf0 block/partitions/core.c:553
bdev_disk_changed+0x238/0x430 fs/block_dev.c:1237
loop_reread_partitions+0x29/0x50 drivers/block/loop.c:655
loop_set_status+0x704/0x1050 drivers/block/loop.c:1418
loop_set_status64 drivers/block/loop.c:1538 [inline]
lo_ioctl+0x4ca/0x1620 drivers/block/loop.c:1706
blkdev_ioctl+0x2a1/0x6d0 block/ioctl.c:583
block_ioctl+0xf9/0x140 fs/block_dev.c:1658
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl fs/ioctl.c:739 [inline]
__x64_sys_ioctl+0x193/0x200 fs/ioctl.c:739
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff8881440f9700
which belongs to the cache bdev_cache of size 2792
The buggy address is located 40 bytes inside of
2792-byte region [ffff8881440f9700, ffff8881440fa1e8)
The buggy address belongs to the page:
page:ffffea0005103e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1440f8
head:ffffea0005103e00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x57ff00000010200(slab|head)
raw: 057ff00000010200 dead000000000100 dead000000000122 ffff8880101bdb40
raw: 0000000000000000 00000000800b000b 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881440f9600: 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc
ffff8881440f9680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881440f9700: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8881440f9780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881440f9800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: 079274f2 block: add a RCU grace period to delete_partition
git tree: git://git.infradead.org/users/hch/block.git
console output: https://syzkaller.appspot.com/x/log.txt?x=11e5c1f6d00000

Ming Lei

unread,
Mar 26, 2021, 4:35:52 AM3/26/21
to syzbot, Jens Axboe, linux-block, Linux Kernel Mailing List, syzkall...@googlegroups.com
On Sun, Mar 14, 2021 at 7:10 PM syzbot
<syzbot+8fede7...@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 280d542f Merge tag 'drm-fixes-2021-03-05' of git://anongit..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15ade5aed00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=952047a9dbff6a6a
> dashboard link: https://syzkaller.appspot.com/bug?extid=8fede7e30c7cee0de139

syzbot

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Mar 26, 2021, 1:01:10 PM3/26/21
to ax...@kernel.dk, linux...@vger.kernel.org, linux-...@vger.kernel.org, syzkall...@googlegroups.com, tom.l...@gmail.com
Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING in kvm_wait

------------[ cut here ]------------
raw_local_irq_restore() called with IRQs enabled
WARNING: CPU: 1 PID: 10753 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x1d/0x20 kernel/locking/irqflag-debug.c:10
Modules linked in:
CPU: 1 PID: 10753 Comm: syz-executor.4 Not tainted 5.12.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:warn_bogus_irq_restore+0x1d/0x20 kernel/locking/irqflag-debug.c:10
Code: be ff cc cc cc cc cc cc cc cc cc cc cc 80 3d a1 e7 2b 04 00 74 01 c3 48 c7 c7 20 92 6b 89 c6 05 90 e7 2b 04 01 e8 79 cf be ff <0f> 0b c3 48 39 77 10 0f 84 97 00 00 00 66 f7 47 22 f0 ff 74 4b 48
RSP: 0018:ffffc90008f0f9c0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: ffff888021f02040 RCX: 0000000000000000
RDX: ffff888017d4d4c0 RSI: ffffffff815c3875 RDI: fffff520011e1f2a
RBP: 0000000000000200 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815bc60e R11: 0000000000000000 R12: 0000000000000003
R13: ffffed10043e0408 R14: 0000000000000001 R15: ffff8880b9f35f40
FS: 00000000022dd400(0000) GS:ffff8880b9f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000004e4a64 CR3: 0000000016964000 CR4: 0000000000350ee0
Call Trace:
kvm_wait arch/x86/kernel/kvm.c:860 [inline]
kvm_wait+0xc9/0xe0 arch/x86/kernel/kvm.c:837
pv_wait arch/x86/include/asm/paravirt.h:564 [inline]
pv_wait_head_or_lock kernel/locking/qspinlock_paravirt.h:470 [inline]
__pv_queued_spin_lock_slowpath+0x8b8/0xb40 kernel/locking/qspinlock.c:508
pv_queued_spin_lock_slowpath arch/x86/include/asm/paravirt.h:554 [inline]
queued_spin_lock_slowpath arch/x86/include/asm/qspinlock.h:51 [inline]
queued_spin_lock include/asm-generic/qspinlock.h:85 [inline]
do_raw_spin_lock+0x200/0x2b0 kernel/locking/spinlock_debug.c:113
spin_lock include/linux/spinlock.h:354 [inline]
ext4_lock_group fs/ext4/ext4.h:3383 [inline]
__ext4_new_inode+0x384f/0x5570 fs/ext4/ialloc.c:1188
ext4_symlink+0x489/0xd50 fs/ext4/namei.c:3347
vfs_symlink fs/namei.c:4176 [inline]
vfs_symlink+0x10f/0x270 fs/namei.c:4161
do_symlinkat+0x27a/0x300 fs/namei.c:4206
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x465d67
Code: 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 58 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffda32c3708 EFLAGS: 00000202 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000465d67
RDX: 00007ffda32c37f3 RSI: 00000000004bfab2 RDI: 00007ffda32c37e0
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffda32c35a0
R10: 00007ffda32c3457 R11: 0000000000000202 R12: 0000000000000001
R13: 0000000000000000 R14: 0000000000000001 R15: 00007ffda32c37e0


Tested on:

commit: c47a2e74 block: not create too many partitions
git tree: https://github.com/ming1/linux.git v5.12-block-test
console output: https://syzkaller.appspot.com/x/log.txt?x=11d037e6d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=b5da36c3359b30d1

Ming Lei

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Mar 27, 2021, 2:50:41 AM3/27/21
to syzbot, Jens Axboe, linux-block, Linux Kernel Mailing List, syzkall...@googlegroups.com
This is another & un-related warning with original report, so I think
the patch in above
tree fixes the issue.


--
Ming Lei
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