From: syzbot <syzbot+83827f9a59abe148bff4@syzkaller.appspotmail.com>
To: agk@redhat.com, bmarzins@redhat.com, dm-devel@lists.linux.dev,
linux-kernel@vger.kernel.org, mpatocka@redhat.com,
snitzer@kernel.org, syzkaller-bugs@googlegroups.com
Subject: [syzbot] [dm?] KASAN: slab-use-after-free Read in pool_ctr
Date: Sun, 25 Oct 2026 19:06:36 -0700 [thread overview]
Message-ID: <6adeb5ac.a6443767.132891.0053.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: 4df4d2a577db Merge tag 'acpi-7.4-rc1' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1640f481580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fe03d9a06fc7d5c0
dashboard link: https://syzkaller.appspot.com/bug?extid=83827f9a59abe148bff4
compiler: Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1140f481580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11246621580000
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-4df4d2a5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ff9ee3e3fda0/vmlinux-4df4d2a5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a29eeaefab21/bzImage-4df4d2a5.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+83827f9a59abe148bff4@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in pool_ctr+0x874/0xd60 drivers/md/dm-thin.c:3363
Read of size 8 at addr ffff8880340cc698 by task syz.0.17/5507
CPU: 0 UID: 0 PID: 5507 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description+0x55/0x1e0 mm/kasan/report.c:378
print_report+0x58/0x70 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
pool_ctr+0x874/0xd60 drivers/md/dm-thin.c:3363
dm_table_add_target+0x58d/0xc70 drivers/md/dm-table.c:749
populate_table drivers/md/dm-ioctl.c:1602 [inline]
table_load+0x325/0x8a0 drivers/md/dm-ioctl.c:1645
ctl_ioctl drivers/md/dm-ioctl.c:2221 [inline]
dm_ctl_ioctl+0x9ec/0xe10 drivers/md/dm-ioctl.c:2243
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fad75f9f559
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe43dedf68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fad76225fa0 RCX: 00007fad75f9f559
RDX: 00002000000003c0 RSI: 00000000c138fd09 RDI: 0000000000000003
RBP: 00007fad76036b20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fad76225fac R14: 00007fad76225fa0 R15: 00007fad76225fa0
</TASK>
Allocated by task 5507:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:409 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:426
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_node_noprof+0x3cc/0x620 mm/slub.c:5582
_kmalloc_node_noprof include/linux/slab.h:1196 [inline]
open_table_device drivers/md/dm.c:733 [inline]
dm_get_table_device+0x23e/0x730 drivers/md/dm.c:821
dm_get_device+0x327/0x760 drivers/md/dm-table.c:388
pool_ctr+0x4ae/0xd60 drivers/md/dm-thin.c:3329
dm_table_add_target+0x58d/0xc70 drivers/md/dm-table.c:749
populate_table drivers/md/dm-ioctl.c:1602 [inline]
table_load+0x325/0x8a0 drivers/md/dm-ioctl.c:1645
ctl_ioctl drivers/md/dm-ioctl.c:2221 [inline]
dm_ctl_ioctl+0x9ec/0xe10 drivers/md/dm-ioctl.c:2243
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 5507:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:264 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:296
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2748 [inline]
slab_free mm/slub.c:6509 [inline]
kfree+0x1c5/0x650 mm/slub.c:6802
close_table_device drivers/md/dm.c:798 [inline]
dm_put_table_device+0x255/0x2a0 drivers/md/dm.c:841
upgrade_mode drivers/md/dm-table.c:326 [inline]
dm_get_device+0x56f/0x760 drivers/md/dm-table.c:399
pool_ctr+0x585/0xd60 drivers/md/dm-thin.c:3336
dm_table_add_target+0x58d/0xc70 drivers/md/dm-table.c:749
populate_table drivers/md/dm-ioctl.c:1602 [inline]
table_load+0x325/0x8a0 drivers/md/dm-ioctl.c:1645
ctl_ioctl drivers/md/dm-ioctl.c:2221 [inline]
dm_ctl_ioctl+0x9ec/0xe10 drivers/md/dm-ioctl.c:2243
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff8880340cc680
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 24 bytes inside of
freed 96-byte region [ffff8880340cc680, ffff8880340cc6e0)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x340cc
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000000 ffff88801c041280 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000200020 00000000f5000000 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 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 2, tgid 2 (kthreadd), ts 9397553089
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1871
prep_new_page mm/page_alloc.c:1879 [inline]
get_page_from_freelist+0x2209/0x2280 mm/page_alloc.c:3943
__alloc_frozen_pages_noprof+0x217/0x5a0 mm/page_alloc.c:5436
alloc_slab_page mm/slub.c:3347 [inline]
allocate_slab+0x7d/0x620 mm/slub.c:3462
new_slab mm/slub.c:3513 [inline]
refill_objects+0x2d5/0x350 mm/slub.c:7418
refill_sheaf mm/slub.c:2885 [inline]
__pcs_replace_empty_main+0x2c8/0x6c0 mm/slub.c:4774
alloc_from_pcs mm/slub.c:4850 [inline]
slab_alloc_node mm/slub.c:4984 [inline]
__kmalloc_cache_node_noprof+0x446/0x620 mm/slub.c:5578
_kmalloc_node_noprof include/linux/slab.h:1196 [inline]
__get_vm_area_node+0x155/0x2f0 mm/vmalloc.c:3237
__vmalloc_node_range_noprof+0x343/0x1540 mm/vmalloc.c:4064
__vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4165
alloc_thread_stack_node kernel/fork.c:359 [inline]
dup_task_struct+0x2c6/0xa00 kernel/fork.c:930
copy_process+0x7ea/0x44b0 kernel/fork.c:2143
kernel_clone+0x2d7/0x940 kernel/fork.c:2785
kernel_thread+0x13f/0x1b0 kernel/fork.c:2846
create_kthread kernel/kthread.c:459 [inline]
kthreadd+0x4ec/0x6e0 kernel/kthread.c:817
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
page last free pid 38 tgid 38 ts 9396138651 stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
__free_pages_prepare mm/page_alloc.c:1418 [inline]
__free_frozen_pages+0xc93/0xd90 mm/page_alloc.c:2962
__kasan_populate_vmalloc_do mm/kasan/shadow.c:393 [inline]
__kasan_populate_vmalloc+0x1a8/0x1c0 mm/kasan/shadow.c:424
kasan_populate_vmalloc include/linux/kasan.h:580 [inline]
alloc_vmap_area+0xd10/0x1410 mm/vmalloc.c:2145
__get_vm_area_node+0x200/0x2f0 mm/vmalloc.c:3248
__vmalloc_node_range_noprof+0x343/0x1540 mm/vmalloc.c:4064
__vmalloc_node_noprof+0xc2/0x100 mm/vmalloc.c:4165
alloc_thread_stack_node kernel/fork.c:359 [inline]
dup_task_struct+0x2c6/0xa00 kernel/fork.c:930
copy_process+0x7ea/0x44b0 kernel/fork.c:2143
kernel_clone+0x2d7/0x940 kernel/fork.c:2785
user_mode_thread+0x115/0x180 kernel/fork.c:2862
call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:169
process_one_work kernel/workqueue.c:3396 [inline]
process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3479
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3560
kthread+0x38b/0x480 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Memory state around the buggy address:
ffff8880340cc580: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
ffff8880340cc600: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
>ffff8880340cc680: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff8880340cc700: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
ffff8880340cc780: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
==================================================================
---
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 syzkaller@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 syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
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 other threads:[~2026-10-26 2:06 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=6adeb5ac.a6443767.132891.0053.GAE@google.com \
--to=syzbot+83827f9a59abe148bff4@syzkaller.appspotmail.com \
--cc=agk@redhat.com \
--cc=bmarzins@redhat.com \
--cc=dm-devel@lists.linux.dev \
--cc=linux-kernel@vger.kernel.org \
--cc=mpatocka@redhat.com \
--cc=snitzer@kernel.org \
--cc=syzkaller-bugs@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.