[moderation] [fs?] KASAN: slab-use-after-free Read in dnotify_flush
1 view
Skip to first unread message
syzbot
12:37 AM (7 hours ago) 12:37 AM
to syzkaller-upst...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 7d31f578f323 Add linux-next specific files for 20251128
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16053912580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6336d8e94a7c517d
dashboard link: https://syzkaller.appspot.com/bug?extid=b7dd06d97df911e34aef
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [amir...@gmail.com ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org]
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6b49d8ad90de/disk-7d31f578.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dbe2d4988ca7/vmlinux-7d31f578.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc0448ab2411/bzImage-7d31f578.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b7dd06...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in dnotify_flush+0x49f/0x5e0 fs/notify/dnotify/dnotify.c:161
Read of size 2 at addr ffff888147283640 by task syz.5.963/10262
CPU: 0 UID: 0 PID: 10262 Comm: syz.5.963 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
dnotify_flush+0x49f/0x5e0 fs/notify/dnotify/dnotify.c:161
filp_flush+0x108/0x190 fs/open.c:1536
__do_sys_close fs/open.c:1567 [inline]
__se_sys_close fs/open.c:1558 [inline]
__x64_sys_close+0x75/0x110 fs/open.c:1558
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0d0438f749
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0d05253038 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f0d045e5fa0 RCX: 00007f0d0438f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f0d04413f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0d045e6038 R14: 00007f0d045e5fa0 R15: 00007ffd1bdca578
</TASK>
Allocated by task 10262:
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
unpoison_slab_object mm/kasan/common.c:339 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:365
kasan_slab_alloc include/linux/kasan.h:252 [inline]
slab_post_alloc_hook mm/slub.c:4948 [inline]
slab_alloc_node mm/slub.c:5258 [inline]
kmem_cache_alloc_lru_noprof+0x36c/0x6e0 mm/slub.c:5277
mqueue_alloc_inode+0x28/0x40 ipc/mqueue.c:502
alloc_inode+0x6a/0x1b0 fs/inode.c:346
new_inode+0x22/0x170 fs/inode.c:1175
mqueue_get_inode+0x27/0xb50 ipc/mqueue.c:297
mqueue_create_attr+0x1ac/0x2e0 ipc/mqueue.c:590
vfs_mkobj+0xcf/0x290 fs/namei.c:4153
prepare_open ipc/mqueue.c:876 [inline]
mqueue_file_open ipc/mqueue.c:905 [inline]
do_mq_open+0x60d/0x7c0 ipc/mqueue.c:928
__do_sys_mq_open ipc/mqueue.c:941 [inline]
__se_sys_mq_open ipc/mqueue.c:934 [inline]
__x64_sys_mq_open+0x16a/0x1c0 ipc/mqueue.c:934
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 15:
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:252 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
kasan_slab_free include/linux/kasan.h:234 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free mm/slub.c:6663 [inline]
kmem_cache_free+0x197/0x620 mm/slub.c:6774
rcu_do_batch kernel/rcu/tree.c:2605 [inline]
rcu_core+0xd70/0x1870 kernel/rcu/tree.c:2857
handle_softirqs+0x27d/0x850 kernel/softirq.c:626
run_ksoftirqd+0x9b/0x100 kernel/softirq.c:1067
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
__call_rcu_common kernel/rcu/tree.c:3119 [inline]
call_rcu+0x157/0x9c0 kernel/rcu/tree.c:3239
destroy_inode fs/inode.c:401 [inline]
evict+0x931/0xae0 fs/inode.c:861
__do_sys_mq_unlink ipc/mqueue.c:972 [inline]
__se_sys_mq_unlink+0x2c5/0x360 ipc/mqueue.c:944
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888147283600
which belongs to the cache mqueue_inode_cache of size 1576
The buggy address is located 64 bytes inside of
freed 1576-byte region [ffff888147283600, ffff888147283c28)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888147282f40 pfn:0x147280
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888143bd2e01
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff8881466b6140 dead000000000122 0000000000000000
raw: ffff888147282f40 000000008012000f 00000000f5000000 ffff888143bd2e01
head: 057ff00000000040 ffff8881466b6140 dead000000000122 0000000000000000
head: ffff888147282f40 000000008012000f 00000000f5000000 ffff888143bd2e01
head: 057ff00000000003 ffffea00051ca001 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 6520806601, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846
prep_new_page mm/page_alloc.c:1854 [inline]
get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3915
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
alloc_slab_page mm/slub.c:3075 [inline]
allocate_slab+0x86/0x3b0 mm/slub.c:3248
new_slab mm/slub.c:3302 [inline]
___slab_alloc+0xf2b/0x1960 mm/slub.c:4651
__slab_alloc+0x65/0x100 mm/slub.c:4774
__slab_alloc_node mm/slub.c:4850 [inline]
slab_alloc_node mm/slub.c:5246 [inline]
kmem_cache_alloc_lru_noprof+0x3fe/0x6e0 mm/slub.c:5277
mqueue_alloc_inode+0x28/0x40 ipc/mqueue.c:502
alloc_inode+0x6a/0x1b0 fs/inode.c:346
new_inode+0x22/0x170 fs/inode.c:1175
mqueue_get_inode ipc/mqueue.c:297 [inline]
mqueue_fill_super+0xdc/0x380 ipc/mqueue.c:416
vfs_get_super fs/super.c:1324 [inline]
get_tree_nodev+0xbb/0x150 fs/super.c:1343
vfs_get_tree+0x92/0x2a0 fs/super.c:1751
fc_mount fs/namespace.c:1209 [inline]
fc_mount_longterm+0x1c/0x100 fs/namespace.c:1220
mq_create_mount ipc/mqueue.c:486 [inline]
mq_init_ns+0x275/0x360 ipc/mqueue.c:1639
page_owner free stack trace missing
Memory state around the buggy address:
ffff888147283500: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
ffff888147283580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888147283600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888147283680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888147283700: 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.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot found the following issue on:
HEAD commit: 7d31f578f323 Add linux-next specific files for 20251128
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16053912580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6336d8e94a7c517d
dashboard link: https://syzkaller.appspot.com/bug?extid=b7dd06d97df911e34aef
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [amir...@gmail.com ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org]
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6b49d8ad90de/disk-7d31f578.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dbe2d4988ca7/vmlinux-7d31f578.xz
kernel image: https://storage.googleapis.com/syzbot-assets/fc0448ab2411/bzImage-7d31f578.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b7dd06...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in dnotify_flush+0x49f/0x5e0 fs/notify/dnotify/dnotify.c:161
Read of size 2 at addr ffff888147283640 by task syz.5.963/10262
CPU: 0 UID: 0 PID: 10262 Comm: syz.5.963 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
dnotify_flush+0x49f/0x5e0 fs/notify/dnotify/dnotify.c:161
filp_flush+0x108/0x190 fs/open.c:1536
__do_sys_close fs/open.c:1567 [inline]
__se_sys_close fs/open.c:1558 [inline]
__x64_sys_close+0x75/0x110 fs/open.c:1558
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0d0438f749
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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0d05253038 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f0d045e5fa0 RCX: 00007f0d0438f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f0d04413f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0d045e6038 R14: 00007f0d045e5fa0 R15: 00007ffd1bdca578
</TASK>
Allocated by task 10262:
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
unpoison_slab_object mm/kasan/common.c:339 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:365
kasan_slab_alloc include/linux/kasan.h:252 [inline]
slab_post_alloc_hook mm/slub.c:4948 [inline]
slab_alloc_node mm/slub.c:5258 [inline]
kmem_cache_alloc_lru_noprof+0x36c/0x6e0 mm/slub.c:5277
mqueue_alloc_inode+0x28/0x40 ipc/mqueue.c:502
alloc_inode+0x6a/0x1b0 fs/inode.c:346
new_inode+0x22/0x170 fs/inode.c:1175
mqueue_get_inode+0x27/0xb50 ipc/mqueue.c:297
mqueue_create_attr+0x1ac/0x2e0 ipc/mqueue.c:590
vfs_mkobj+0xcf/0x290 fs/namei.c:4153
prepare_open ipc/mqueue.c:876 [inline]
mqueue_file_open ipc/mqueue.c:905 [inline]
do_mq_open+0x60d/0x7c0 ipc/mqueue.c:928
__do_sys_mq_open ipc/mqueue.c:941 [inline]
__se_sys_mq_open ipc/mqueue.c:934 [inline]
__x64_sys_mq_open+0x16a/0x1c0 ipc/mqueue.c:934
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 15:
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:252 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
kasan_slab_free include/linux/kasan.h:234 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free mm/slub.c:6663 [inline]
kmem_cache_free+0x197/0x620 mm/slub.c:6774
rcu_do_batch kernel/rcu/tree.c:2605 [inline]
rcu_core+0xd70/0x1870 kernel/rcu/tree.c:2857
handle_softirqs+0x27d/0x850 kernel/softirq.c:626
run_ksoftirqd+0x9b/0x100 kernel/softirq.c:1067
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
Last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
__call_rcu_common kernel/rcu/tree.c:3119 [inline]
call_rcu+0x157/0x9c0 kernel/rcu/tree.c:3239
destroy_inode fs/inode.c:401 [inline]
evict+0x931/0xae0 fs/inode.c:861
__do_sys_mq_unlink ipc/mqueue.c:972 [inline]
__se_sys_mq_unlink+0x2c5/0x360 ipc/mqueue.c:944
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888147283600
which belongs to the cache mqueue_inode_cache of size 1576
The buggy address is located 64 bytes inside of
freed 1576-byte region [ffff888147283600, ffff888147283c28)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888147282f40 pfn:0x147280
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff888143bd2e01
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff8881466b6140 dead000000000122 0000000000000000
raw: ffff888147282f40 000000008012000f 00000000f5000000 ffff888143bd2e01
head: 057ff00000000040 ffff8881466b6140 dead000000000122 0000000000000000
head: ffff888147282f40 000000008012000f 00000000f5000000 ffff888143bd2e01
head: 057ff00000000003 ffffea00051ca001 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 6520806601, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846
prep_new_page mm/page_alloc.c:1854 [inline]
get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3915
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
alloc_slab_page mm/slub.c:3075 [inline]
allocate_slab+0x86/0x3b0 mm/slub.c:3248
new_slab mm/slub.c:3302 [inline]
___slab_alloc+0xf2b/0x1960 mm/slub.c:4651
__slab_alloc+0x65/0x100 mm/slub.c:4774
__slab_alloc_node mm/slub.c:4850 [inline]
slab_alloc_node mm/slub.c:5246 [inline]
kmem_cache_alloc_lru_noprof+0x3fe/0x6e0 mm/slub.c:5277
mqueue_alloc_inode+0x28/0x40 ipc/mqueue.c:502
alloc_inode+0x6a/0x1b0 fs/inode.c:346
new_inode+0x22/0x170 fs/inode.c:1175
mqueue_get_inode ipc/mqueue.c:297 [inline]
mqueue_fill_super+0xdc/0x380 ipc/mqueue.c:416
vfs_get_super fs/super.c:1324 [inline]
get_tree_nodev+0xbb/0x150 fs/super.c:1343
vfs_get_tree+0x92/0x2a0 fs/super.c:1751
fc_mount fs/namespace.c:1209 [inline]
fc_mount_longterm+0x1c/0x100 fs/namespace.c:1220
mq_create_mount ipc/mqueue.c:486 [inline]
mq_init_ns+0x275/0x360 ipc/mqueue.c:1639
page_owner free stack trace missing
Memory state around the buggy address:
ffff888147283500: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc
ffff888147283580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888147283600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888147283680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888147283700: 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.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
Reply all
Reply to author
Forward
0 new messages