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

[syzbot]

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.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

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]

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

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

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]

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]

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]

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]

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]

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]

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]

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

dashboard link: https://syzkaller.appspot.com/bug?extid=8fede7e30c7cee0de139
compiler:

patch: https://syzkaller.appspot.com/x/patch.diff?x=14d738bed00000

[Ming Lei]

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]

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]

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]

#syz test: git://git.infradead.org/users/hch/block.git part-iter-fix

---end quoted text---

[syzbot]

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]

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]

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]

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]

This is another & un-related warning with original report, so I think
the patch in above
tree fixes the issue.


--
Ming Lei