KASAN: slab-use-after-free Read in snapshot_ctr

Status: premoderation: reported C repro on 2026/10/20 20:44
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+0dce8662d0b95fade7cb@syzkaller.appspotmail.com
First crash: 15d, last: 8h29m
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/10/24 lts (merge base) [unknown] C Failed due to an error; will retry later
2026/10/24 upstream (ToT) 17bb0e2f6c80 C [report] KASAN: slab-use-after-free Read in snapshot_ctr
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: slab-use-after-free Read in snapshot_ctr 19 syz, C 7 7d01h 10d 0/2 upstream: reported C repro on 2026/10/26 07:45
upstream KASAN: slab-use-after-free Read in snapshot_ctr prio:normal dm 19 syz, C 385 44m 12d 0/29 upstream: reported C repro on 2026/10/24 15:49

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in snapshot_ctr+0x586/0x1350 drivers/md/dm-snap.c:1288
Read of size 8 at addr ffff8881052cd498 by task syz-executor308/313

CPU: 1 UID: 0 PID: 313 Comm: syz-executor308 Not tainted syzkaller #0 89738cdce93e33c1079eaf7360b55d01ca9e3330
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 print_address_description+0x71/0x210 mm/kasan/report.c:377
 print_report+0x4a/0x70 mm/kasan/report.c:481
 kasan_report+0x162/0x1a0 mm/kasan/report.c:594
 __asan_report_load8_noabort+0x18/0x20 mm/kasan/report_generic.c:381
 snapshot_ctr+0x586/0x1350 drivers/md/dm-snap.c:1288
 dm_table_add_target+0x59f/0xcb0 drivers/md/dm-table.c:760
 populate_table drivers/md/dm-ioctl.c:1494 [inline]
 table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536
 ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline]
 dm_ctl_ioctl+0x8f0/0xde0 drivers/md/dm-ioctl.c:2129
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892
 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892
 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f6cd31b3fb9
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd349c5b68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffd349c5c98 RCX: 00007f6cd31b3fb9
RDX: 0000200000000500 RSI: 00000000c138fd09 RDI: 0000000000000003
RBP: 0000000000000001 R08: 0000000000000013 R09: 00007ffd349c5c98
R10: 0000000000000001 R11: 0000000000000246 R12: 00007ffd349c5c88
R13: 0000000000000002 R14: 00007f6cd3244ca0 R15: 0000000000000002
 </TASK>

Allocated by task 313:
 kasan_save_stack mm/kasan/common.c:49 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
 kasan_save_alloc_info+0x3a/0x50 mm/kasan/generic.c:565
 poison_kmalloc_redzone mm/kasan/common.c:379 [inline]
 __kasan_kmalloc+0x96/0xb0 mm/kasan/common.c:396
 kasan_kmalloc include/linux/kasan.h:261 [inline]
 __kmalloc_cache_node_noprof+0x225/0x430 mm/slub.c:4440
 kmalloc_node_noprof include/linux/slab.h:1004 [inline]
 open_table_device drivers/md/dm.c:758 [inline]
 dm_get_table_device+0x1e3/0x6c0 drivers/md/dm.c:837
 dm_get_device+0x32b/0x7f0 drivers/md/dm-table.c:394
 snapshot_ctr+0x292/0x1350 drivers/md/dm-snap.c:1273
 dm_table_add_target+0x59f/0xcb0 drivers/md/dm-table.c:760
 populate_table drivers/md/dm-ioctl.c:1494 [inline]
 table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536
 ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline]
 dm_ctl_ioctl+0x8f0/0xde0 drivers/md/dm-ioctl.c:2129
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892
 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892
 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Freed by task 313:
 kasan_save_stack mm/kasan/common.c:49 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
 kasan_save_free_info+0x44/0x50 mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:249 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:266
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2445 [inline]
 slab_free mm/slub.c:4716 [inline]
 kfree+0x158/0x440 mm/slub.c:4877
 close_table_device drivers/md/dm.c:814 [inline]
 dm_put_table_device+0x298/0x2e0 drivers/md/dm.c:857
 upgrade_mode drivers/md/dm-table.c:328 [inline]
 dm_get_device+0x571/0x7f0 drivers/md/dm-table.c:405
 snapshot_ctr+0x435/0x1350 drivers/md/dm-snap.c:1283
 dm_table_add_target+0x59f/0xcb0 drivers/md/dm-table.c:760
 populate_table drivers/md/dm-ioctl.c:1494 [inline]
 table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536
 ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline]
 dm_ctl_ioctl+0x8f0/0xde0 drivers/md/dm-ioctl.c:2129
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892
 __x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892
 x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e

The buggy address belongs to the object at ffff8881052cd480
 which belongs to the cache kmalloc-96 of size 96
The buggy address is located 24 bytes inside of
 freed 96-byte region [ffff8881052cd480, ffff8881052cd4e0)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1052cd
anon flags: 0x4000000000000000(zone=1)
page_type: f5(slab)
raw: 4000000000000000 ffff888100041280 ffffea000413ad40 0000000000000003
raw: 0000000000000000 0000000080200020 00000001f5000000 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 0x52cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 2981654613, free_ts 0
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook+0x37d/0x3b0 mm/page_alloc.c:1864
 prep_new_page+0x2d/0x180 mm/page_alloc.c:1872
 get_page_from_freelist+0x4aea/0x4ba0 mm/page_alloc.c:3949
 __alloc_pages_noprof+0x35a/0x7e0 mm/page_alloc.c:5316
 alloc_slab_page+0x6b/0x1e0 mm/slub.c:-1
 allocate_slab+0x69/0x430 mm/slub.c:2687
 new_slab mm/slub.c:2741 [inline]
 ___slab_alloc+0x591/0x8c0 mm/slub.c:3934
 __slab_alloc mm/slub.c:4025 [inline]
 __slab_alloc_node mm/slub.c:4078 [inline]
 slab_alloc_node mm/slub.c:4241 [inline]
 __kmalloc_cache_noprof+0x2cd/0x470 mm/slub.c:4423
 kmalloc_noprof include/linux/slab.h:882 [inline]
 kzalloc_noprof include/linux/slab.h:1117 [inline]
 call_usermodehelper_setup+0x97/0x300 kernel/umh.c:363
 kobject_uevent_env+0x65f/0x7e0 lib/kobject_uevent.c:628
 kobject_uevent+0x21/0x40 lib/kobject_uevent.c:656
 device_add+0x599/0xbf0 drivers/base/core.c:3673
 input_register_device+0x9af/0x1080 drivers/input/input.c:2470
 acpi_button_add+0x6bc/0xc20 drivers/acpi/button.c:615
 acpi_device_probe+0xc2/0x270 drivers/acpi/bus.c:1076
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x2e1/0x8b0 drivers/base/dd.c:657
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881052cd380: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8881052cd400: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff8881052cd480: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
                            ^
 ffff8881052cd500: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff8881052cd580: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================
device-mapper: table: 252:0: device 1:0 not in table devices list
device-mapper: table: 252:0: snapshot: COW device cannot be the same as origin device (-EINVAL)
device-mapp

Crashes (110):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/27 01:14 android16-6.12 e9c13b0731b0 168cb7a2 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/20 22:13 android16-6.12 3e51fbb70e49 df8746fb .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/20 21:43 android16-6.12 3e51fbb70e49 df8746fb .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/20 21:13 android16-6.12 3e51fbb70e49 df8746fb .config strace log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/05 08:00 android16-6.12 04c605a74ee4 2ee8459f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/05 05:48 android16-6.12 a02a58da719e 73438ed0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/05 03:39 android16-6.12 a02a58da719e 73438ed0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/05 02:19 android16-6.12 a02a58da719e 73438ed0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/04 09:11 android16-6.12 4f89cba38956 5af5b6c6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/04 05:44 android16-6.12 4f89cba38956 5af5b6c6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/04 02:28 android16-6.12 8237c860d45d e2d35131 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/04 01:45 android16-6.12 8237c860d45d e2d35131 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/03 23:35 android16-6.12 8237c860d45d e2d35131 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/03 17:51 android16-6.12 8237c860d45d e2d35131 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/02 20:12 android16-6.12 e92b73070f9a 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/02 14:28 android16-6.12 e92b73070f9a 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/01 19:43 android16-6.12 82e784616179 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/01 14:50 android16-6.12 abad7aaa7f9f 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/01 12:00 android16-6.12 abad7aaa7f9f 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/01 09:20 android16-6.12 abad7aaa7f9f 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/11/01 08:09 android16-6.12 abad7aaa7f9f 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/31 20:36 android16-6.12 d0858d6982b2 2041d3f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/31 18:54 android16-6.12 d0858d6982b2 2041d3f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/31 17:49 android16-6.12 d0858d6982b2 2041d3f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/31 15:07 android16-6.12 d0858d6982b2 2041d3f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/31 11:18 android16-6.12 d0858d6982b2 2041d3f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/31 05:04 android16-6.12 21e8b8d58095 0ec395f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/31 02:27 android16-6.12 21e8b8d58095 0ec395f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/30 08:24 android16-6.12 c244ab6f4052 b498adee .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/30 06:12 android16-6.12 c244ab6f4052 b498adee .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/30 05:01 android16-6.12 c244ab6f4052 b498adee .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 18:44 android16-6.12 0f8e720fcdfb b498adee .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 17:02 android16-6.12 0f8e720fcdfb b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 14:46 android16-6.12 0f8e720fcdfb b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 12:51 android16-6.12 0f8e720fcdfb b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 10:22 android16-6.12 0f8e720fcdfb b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 09:32 android16-6.12 0f8e720fcdfb b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 07:45 android16-6.12 0f8e720fcdfb b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 06:36 android16-6.12 0f8e720fcdfb b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 05:32 android16-6.12 0f8e720fcdfb b1d00f76 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/29 02:12 android16-6.12 0f8e720fcdfb 858db2ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/28 16:27 android16-6.12 606d03f6372c 858db2ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/28 15:03 android16-6.12 606d03f6372c 858db2ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/28 07:59 android16-6.12 606d03f6372c 96923c60 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/28 03:52 android16-6.12 4db94d79f511 96923c60 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/28 02:17 android16-6.12 4db94d79f511 96923c60 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/27 13:45 android16-6.12 3b7cac078605 168cb7a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/27 11:36 android16-6.12 3b7cac078605 168cb7a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/27 09:05 android16-6.12 3b7cac078605 168cb7a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/27 07:57 android16-6.12 3b7cac078605 168cb7a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/27 05:27 android16-6.12 3b7cac078605 168cb7a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/27 01:55 android16-6.12 e9c13b0731b0 168cb7a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
2026/10/27 01:42 android16-6.12 e9c13b0731b0 168cb7a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust KASAN: slab-use-after-free Read in snapshot_ctr
* Struck through repros no longer work on HEAD.