[syzbot] [nilfs?] KASAN: slab-use-after-free Write in nilfs_inode_sub_blocks

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 16a8829130ca nfs: fix another case of NULL/IS_ERR confusio..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14d4918e280000
kernel config: https://syzkaller.appspot.com/x/.config?x=38526bf24c8d961b
dashboard link: https://syzkaller.appspot.com/bug?extid=9e707f43f54a997a3d24
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3ce65c9fe5fa/disk-16a88291.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3b31187819e4/vmlinux-16a88291.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bf345be82c12/bzImage-16a88291.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9e707f...@syzkaller.appspotmail.com

NILFS (loop2): discard dirty block: blocknr=18446744073709551615, size=1024
NILFS (loop2): discard dirty block: blocknr=18446744073709551615, size=1024
NILFS (loop2): discard dirty block: blocknr=18446744073709551615, size=1024
==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: slab-use-after-free in atomic64_sub include/linux/atomic/atomic-instrumented.h:764 [inline]
BUG: KASAN: slab-use-after-free in nilfs_inode_sub_blocks+0x97/0xe0 fs/nilfs2/inode.c:61
Write of size 8 at addr ffff88807abb5240 by task syz-executor.2/5038

CPU: 0 PID: 5038 Comm: syz-executor.2 Not tainted 6.4.0-rc1-syzkaller-00012-g16a8829130ca #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:351 [inline]
print_report+0x163/0x540 mm/kasan/report.c:462
kasan_report+0x176/0x1b0 mm/kasan/report.c:572
kasan_check_range+0x283/0x290 mm/kasan/generic.c:187
instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
atomic64_sub include/linux/atomic/atomic-instrumented.h:764 [inline]
nilfs_inode_sub_blocks+0x97/0xe0 fs/nilfs2/inode.c:61
nilfs_direct_delete+0x27e/0x310 fs/nilfs2/direct.c:159
nilfs_bmap_do_delete fs/nilfs2/bmap.c:184 [inline]
nilfs_bmap_do_truncate fs/nilfs2/bmap.c:272 [inline]
nilfs_bmap_truncate+0x300/0x560 fs/nilfs2/bmap.c:305
nilfs_truncate_bmap+0x207/0x3d0 fs/nilfs2/inode.c:846
nilfs_evict_inode+0x17c/0x420 fs/nilfs2/inode.c:933
evict+0x2a4/0x620 fs/inode.c:665
nilfs_dispose_list+0x51d/0x5c0 fs/nilfs2/segment.c:816
nilfs_detach_log_writer+0xaf1/0xbb0 fs/nilfs2/segment.c:2852
nilfs_put_super+0x4d/0x160 fs/nilfs2/super.c:477
generic_shutdown_super+0x134/0x340 fs/super.c:500
kill_block_super+0x84/0xf0 fs/super.c:1407
deactivate_locked_super+0xa4/0x110 fs/super.c:331
cleanup_mnt+0x426/0x4c0 fs/namespace.c:1177
task_work_run+0x24a/0x300 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:297
do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f545728d5d7
Code: ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff87fdfd18 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f545728d5d7
RDX: 00007fff87fdfdeb RSI: 000000000000000a RDI: 00007fff87fdfde0
RBP: 00007fff87fdfde0 R08: 00000000ffffffff R09: 00007fff87fdfbb0
R10: 00005555563268b3 R11: 0000000000000246 R12: 00007f54572e6cdc
R13: 00007fff87fe0ea0 R14: 0000555556326810 R15: 00007fff87fe0ee0
</TASK>

Allocated by task 13219:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
kmalloc include/linux/slab.h:559 [inline]
kzalloc include/linux/slab.h:680 [inline]
nilfs_find_or_create_root+0x137/0x4e0 fs/nilfs2/the_nilfs.c:810
nilfs_attach_checkpoint+0x123/0x4d0 fs/nilfs2/super.c:529
nilfs_fill_super+0x321/0x600 fs/nilfs2/super.c:1074
nilfs_mount+0x67d/0x9a0 fs/nilfs2/super.c:1326
legacy_get_tree+0xef/0x190 fs/fs_context.c:610
vfs_get_tree+0x8c/0x270 fs/super.c:1510
do_new_mount+0x28f/0xae0 fs/namespace.c:3039
do_mount fs/namespace.c:3382 [inline]
__do_sys_mount fs/namespace.c:3591 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3568
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5038:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:521
____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
kasan_slab_free include/linux/kasan.h:162 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook mm/slub.c:1807 [inline]
slab_free mm/slub.c:3786 [inline]
__kmem_cache_free+0x264/0x3c0 mm/slub.c:3799
nilfs_evict_inode+0x103/0x420 fs/nilfs2/inode.c:925
evict+0x2a4/0x620 fs/inode.c:665
nilfs_dispose_list+0x51d/0x5c0 fs/nilfs2/segment.c:816
nilfs_detach_log_writer+0xaf1/0xbb0 fs/nilfs2/segment.c:2852
nilfs_put_super+0x4d/0x160 fs/nilfs2/super.c:477
generic_shutdown_super+0x134/0x340 fs/super.c:500
kill_block_super+0x84/0xf0 fs/super.c:1407
deactivate_locked_super+0xa4/0x110 fs/super.c:331
cleanup_mnt+0x426/0x4c0 fs/namespace.c:1177
task_work_run+0x24a/0x300 kernel/task_work.c:179
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:297
do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88807abb5200
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 64 bytes inside of
freed 256-byte region [ffff88807abb5200, ffff88807abb5300)

The buggy address belongs to the physical page:
page:ffffea0001eaed00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7abb4
head:ffffea0001eaed00 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000010200 ffff888012441b40 ffffea0000a82100 dead000000000004
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5142, tgid 5142 (udevd), ts 305278177864, free_ts 305225685128
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1731
prep_new_page mm/page_alloc.c:1738 [inline]
get_page_from_freelist+0x321c/0x33a0 mm/page_alloc.c:3502
__alloc_pages+0x255/0x670 mm/page_alloc.c:4768
alloc_slab_page+0x6a/0x160 mm/slub.c:1851
allocate_slab mm/slub.c:1998 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2051
___slab_alloc+0xa85/0x10a0 mm/slub.c:3192
__slab_alloc mm/slub.c:3291 [inline]
__slab_alloc_node mm/slub.c:3344 [inline]
slab_alloc_node mm/slub.c:3441 [inline]
__kmem_cache_alloc_node+0x1b8/0x290 mm/slub.c:3490
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1057
kmalloc include/linux/slab.h:559 [inline]
kzalloc include/linux/slab.h:680 [inline]
smk_fetch+0x92/0x140 security/smack/smack_lsm.c:291
smack_d_instantiate+0x868/0xb40 security/smack/smack_lsm.c:3512
security_d_instantiate+0x9b/0xf0 security/security.c:3760
d_instantiate+0x55/0x90 fs/dcache.c:2034
shmem_symlink+0x5a6/0x750 mm/shmem.c:3195
vfs_symlink+0x12f/0x2a0 fs/namei.c:4475
do_symlinkat+0x201/0x610 fs/namei.c:4501
__do_sys_symlink fs/namei.c:4522 [inline]
__se_sys_symlink fs/namei.c:4520 [inline]
__x64_sys_symlink+0x7e/0x90 fs/namei.c:4520
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1302 [inline]
free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2564
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2659
qlist_free_all+0x22/0x60 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:186 [inline]
slab_post_alloc_hook+0x68/0x3a0 mm/slab.h:711
slab_alloc_node mm/slub.c:3451 [inline]
__kmem_cache_alloc_node+0x14c/0x290 mm/slub.c:3490
__do_kmalloc_node mm/slab_common.c:965 [inline]
__kmalloc+0xa8/0x230 mm/slab_common.c:979
kmalloc include/linux/slab.h:563 [inline]
tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x254/0x4e0 security/tomoyo/file.c:771
security_file_open+0x63/0xa0 security/security.c:2797
do_dentry_open+0x308/0x10f0 fs/open.c:907
do_open fs/namei.c:3636 [inline]
path_openat+0x27b3/0x3170 fs/namei.c:3791
do_filp_open+0x234/0x490 fs/namei.c:3818
do_sys_openat2+0x13f/0x500 fs/open.c:1356
do_sys_open fs/open.c:1372 [inline]
__do_sys_openat fs/open.c:1388 [inline]
__se_sys_openat fs/open.c:1383 [inline]
__x64_sys_openat+0x247/0x290 fs/open.c:1383

Memory state around the buggy address:
ffff88807abb5100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88807abb5180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88807abb5200: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807abb5280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807abb5300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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[Ryusuke Konishi]

According to the call trace, this issue hits an issue with the same
root cause as reported by "[syzbot] [nilfs?] KASAN:
slab-use-after-free Read in nilfs_load_inode_block", and will be fixed
by the on-going patch below:

#syz fix: nilfs2: fix use-after-free bug of nilfs_root in nilfs_evict_inode()

Ryusuke Konishi