==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:72 [inline]
BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in kernfs_get+0x21/0x90 fs/kernfs/dir.c:525
Read of size 4 at addr ffff888130a7a898 by task kworker/0:0/6442
CPU: 0 PID: 6442 Comm: kworker/0:0 Tainted: G W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events flush_stashed_error_work
Call Trace:
<TASK>
__dump_stack+0x21/0x24 lib/dump_stack.c:88
dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
print_address_description+0x71/0x200 mm/kasan/report.c:316
print_report+0x4a/0x60 mm/kasan/report.c:420
kasan_report+0x122/0x150 mm/kasan/report.c:524
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
__kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31
instrument_atomic_read include/linux/instrumented.h:72 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
kernfs_get+0x21/0x90 fs/kernfs/dir.c:525
sysfs_notify+0x5a/0xd0 fs/sysfs/file.c:187
ext4_notify_error_sysfs+0x25/0x30 fs/ext4/sysfs.c:518
flush_stashed_error_work+0x2cb/0x2f0 fs/ext4/super.c:-1
process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
worker_thread+0xa29/0x11e0 kernel/workqueue.c:2449
kthread+0x281/0x320 kernel/kthread.c:386
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Allocated by task 9859:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505
__kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:334
kasan_slab_alloc include/linux/kasan.h:202 [inline]
slab_post_alloc_hook+0x4f/0x2d0 mm/slab.h:768
slab_alloc_node mm/slub.c:3382 [inline]
slab_alloc mm/slub.c:3392 [inline]
__kmem_cache_alloc_lru mm/slub.c:3399 [inline]
kmem_cache_alloc+0x16e/0x330 mm/slub.c:3408
kmem_cache_zalloc include/linux/slab.h:689 [inline]
__kernfs_new_node+0xe3/0x6b0 fs/kernfs/dir.c:614
kernfs_new_node+0x150/0x260 fs/kernfs/dir.c:690
kernfs_create_dir_ns+0x47/0x130 fs/kernfs/dir.c:1046
sysfs_create_dir_ns+0x128/0x290 fs/sysfs/dir.c:59
create_dir lib/kobject.c:63 [inline]
kobject_add_internal+0x714/0xc30 lib/kobject.c:231
kobject_add_varg lib/kobject.c:366 [inline]
kobject_init_and_add+0x128/0x190 lib/kobject.c:449
ext4_register_sysfs+0xbb/0x2c0 fs/ext4/sysfs.c:531
__ext4_fill_super fs/ext4/super.c:5519 [inline]
ext4_fill_super+0x6a29/0x7590 fs/ext4/super.c:5674
get_tree_bdev+0x447/0x690 fs/super.c:1371
ext4_get_tree+0x1c/0x20 fs/ext4/super.c:5704
vfs_get_tree+0x9a/0x270 fs/super.c:1578
do_new_mount+0x251/0xb30 fs/namespace.c:3081
path_mount+0x659/0xfc0 fs/namespace.c:3411
do_mount fs/namespace.c:3424 [inline]
__do_sys_mount fs/namespace.c:3632 [inline]
__se_sys_mount+0x320/0x390 fs/namespace.c:3609
__x64_sys_mount+0xbf/0xd0 fs/namespace.c:3609
x64_sys_call+0x65d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Freed by task 6473:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x31/0x50 mm/kasan/generic.c:516
____kasan_slab_free+0x132/0x180 mm/kasan/common.c:242
__kasan_slab_free+0x11/0x20 mm/kasan/common.c:250
kasan_slab_free include/linux/kasan.h:178 [inline]
slab_free_hook mm/slub.c:1750 [inline]
slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1776
slab_free mm/slub.c:3712 [inline]
kmem_cache_free+0x12d/0x300 mm/slub.c:3737
kernfs_put+0x310/0x480 fs/kernfs/dir.c:568
sysfs_put include/linux/sysfs.h:696 [inline]
__kobject_del+0xf8/0x2f0 lib/kobject.c:597
kobject_del+0x45/0x60 lib/kobject.c:619
ext4_unregister_sysfs+0x91/0xa0 fs/ext4/sysfs.c:565
ext4_put_super+0x73/0xac0 fs/ext4/super.c:1216
generic_shutdown_super+0x16c/0x480 fs/super.c:506
kill_block_super+0x7f/0xf0 fs/super.c:1475
deactivate_locked_super+0xb5/0x120 fs/super.c:336
deactivate_super+0xaf/0xe0 fs/super.c:367
cleanup_mnt+0x474/0x500 fs/namespace.c:1192
__cleanup_mnt+0x19/0x20 fs/namespace.c:1199
task_work_run+0x1e1/0x250 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0x9b/0xb0 kernel/entry/common.c:177
exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff888130a7a898
which belongs to the cache kernfs_node_cache of size 136
The buggy address is located 0 bytes inside of
136-byte region [ffff888130a7a898, ffff888130a7a920)
The buggy address belongs to the physical page:
page:ffffea0004c29e80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x130a7a
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 ffffea0004c29d80 dead000000000007 ffff8881001ecf00
raw: 0000000000000000 0000000000140014 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 286, tgid 286 (syz-executor), ts 25790563104, free_ts 0
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2670
prep_new_page+0x1c/0x110 mm/page_alloc.c:2677
get_page_from_freelist+0x2d12/0x2d80 mm/page_alloc.c:4583
__alloc_pages+0x1fa/0x610 mm/page_alloc.c:5924
alloc_slab_page+0x6e/0xf0 include/linux/gfp.h:-1
allocate_slab mm/slub.c:1967 [inline]
new_slab+0x98/0x3d0 mm/slub.c:2020
___slab_alloc+0x6bd/0xb20 mm/slub.c:3177
__slab_alloc+0x5e/0xa0 mm/slub.c:3263
slab_alloc_node mm/slub.c:3348 [inline]
slab_alloc mm/slub.c:3392 [inline]
__kmem_cache_alloc_lru mm/slub.c:3399 [inline]
kmem_cache_alloc+0x1b0/0x330 mm/slub.c:3408
kmem_cache_zalloc include/linux/slab.h:689 [inline]
__kernfs_new_node+0xe3/0x6b0 fs/kernfs/dir.c:614
kernfs_new_node+0x150/0x260 fs/kernfs/dir.c:690
__kernfs_create_file+0x4e/0x270 fs/kernfs/file.c:1068
sysfs_add_file_mode_ns+0x1ce/0x270 fs/sysfs/file.c:294
create_files fs/sysfs/group.c:76 [inline]
internal_create_group+0x72a/0xf50 fs/sysfs/group.c:176
internal_create_groups fs/sysfs/group.c:216 [inline]
sysfs_create_groups+0x58/0x120 fs/sysfs/group.c:242
create_dir lib/kobject.c:68 [inline]
kobject_add_internal+0x753/0xc30 lib/kobject.c:231
page_owner free stack trace missing
Memory state around the buggy address:
ffff888130a7a780: fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb fb
ffff888130a7a800: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc
>ffff888130a7a880: fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888130a7a900: fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb fb
ffff888130a7a980: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
==================================================================
general protection fault, probably for non-canonical address 0xe0a81c2ac0000333: 0000 [#1] PREEMPT SMP KASAN
KASAN: maybe wild-memory-access in range [0x0541015600001998-0x054101560000199f]
CPU: 0 PID: 6442 Comm: kworker/0:0 Tainted: G B W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Workqueue: events flush_stashed_error_work
RIP: 0010:kernfs_root fs/kernfs/kernfs-internal.h:68 [inline]
RIP: 0010:kernfs_find_and_get_ns+0x54/0x110 fs/kernfs/dir.c:903
Code: 48 89 f8 48 c1 e8 03 42 80 3c 28 00 74 05 e8 13 c9 d5 ff 49 8b 5c 24 08 48 85 db 49 0f 44 dc 48 83 c3 50 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 ed c8 d5 ff 48 8b 1b 48 83 c3 60
RSP: 0018:ffffc900127e7c60 EFLAGS: 00010206
RAX: 00a8202ac0000333 RBX: 0541015600001999 RCX: ffffffff81e1025d
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888130a7a8a0
RBP: ffffc900127e7c88 R08: 0000000000000003 R09: fffffffffffffffa
R10: dffffc0000000000 R11: ffffed102614f513 R12: ffff888130a7a898
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffffff85b53420
FS: 0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000133f64000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
kernfs_find_and_get include/linux/kernfs.h:614 [inline]
sysfs_notify+0x71/0xd0 fs/sysfs/file.c:190
ext4_notify_error_sysfs+0x25/0x30 fs/ext4/sysfs.c:518
flush_stashed_error_work+0x2cb/0x2f0 fs/ext4/super.c:-1
process_one_work+0x71f/0xc40 kernel/workqueue.c:2302
worker_thread+0xa29/0x11e0 kernel/workqueue.c:2449
kthread+0x281/0x320 kernel/kthread.c:386
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kernfs_root fs/kernfs/kernfs-internal.h:68 [inline]
RIP: 0010:kernfs_find_and_get_ns+0x54/0x110 fs/kernfs/dir.c:903
Code: 48 89 f8 48 c1 e8 03 42 80 3c 28 00 74 05 e8 13 c9 d5 ff 49 8b 5c 24 08 48 85 db 49 0f 44 dc 48 83 c3 50 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 74 08 48 89 df e8 ed c8 d5 ff 48 8b 1b 48 83 c3 60
RSP: 0018:ffffc900127e7c60 EFLAGS: 00010206
RAX: 00a8202ac0000333 RBX: 0541015600001999 RCX: ffffffff81e1025d
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff888130a7a8a0
RBP: ffffc900127e7c88 R08: 0000000000000003 R09: fffffffffffffffa
R10: dffffc0000000000 R11: ffffed102614f513 R12: ffff888130a7a898
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffffff85b53420
FS: 0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055555f6d0908 CR3: 0000000132c2b000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 48 89 f8 mov %rdi,%rax
3: 48 c1 e8 03 shr $0x3,%rax
7: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1)
c: 74 05 je 0x13
e: e8 13 c9 d5 ff call 0xffd5c926
13: 49 8b 5c 24 08 mov 0x8(%r12),%rbx
18: 48 85 db test %rbx,%rbx
1b: 49 0f 44 dc cmove %r12,%rbx
1f: 48 83 c3 50 add $0x50,%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 48 89 df mov %rbx,%rdi
34: e8 ed c8 d5 ff call 0xffd5c926
39: 48 8b 1b mov (%rbx),%rbx
3c: 48 83 c3 60 add $0x60,%rbx