KASAN: slab-use-after-free Write in xlog_cil_push_work

Status: upstream: reported C repro on 2026/09/22 00:13
Subsystems: xfs
Labels: prio:normal actionable
[Documentation on labels]
Reported-by: syzbot+c32ff62cf4913d345d0c@syzkaller.appspotmail.com
First crash: 13d, last: 4d21h
Cause bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (4)
ID Workflow Result Correct Bug Created Started Finished Revision
813c0ac7 patching 🏃 KASAN: slab-use-after-free Write in xlog_cil_push_work 2026/09/30 20:03 2026/09/30 20:03 38f7f0d1
4823dc1a repro-c 💥 KASAN: slab-use-after-free Write in xlog_cil_push_work 2026/09/24 13:11 2026/09/24 13:11 2026/09/24 16:22 3c3cdf19
58994635 moderation Actionable: ✅ ❓ KASAN: slab-use-after-free Write in xlog_cil_push_work 2026/09/22 00:00 2026/09/22 00:00 2026/09/22 00:12 853b104b
163d2864 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Write in xlog_cil_push_work 2026/09/19 00:00 2026/09/19 00:00 2026/09/19 00:53 853b104b
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [xfs?] KASAN: slab-use-after-free Write in xlog_cil_push_work 0 (2) 2026/09/26 01:31
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream BUG: unable to handle kernel paging request in xlog_cil_push_work xfs 8 5 518d 518d 0/29 auto-obsoleted due to no activity on 2025/08/08 19:37
upstream KASAN: slab-use-after-free Read in xlog_cil_push_work xfs 19 syz, C error 4 255d 405d 0/29 auto-obsoleted due to no activity on 2026/04/28 05:38
upstream KASAN: slab-out-of-bounds Write in xlog_cil_push_work xfs 22 3 844d 850d 0/29 auto-obsoleted due to no activity on 2024/09/06 14:39
upstream KASAN: slab-use-after-free Read in xlog_cil_push_work (2) prio:high xfs 19 5 142d 138d 0/29 auto-obsoleted due to no activity on 2026/08/19 15:34

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __list_splice include/linux/list.h:577 [inline]
BUG: KASAN: slab-use-after-free in list_splice_init include/linux/list.h:619 [inline]
BUG: KASAN: slab-use-after-free in xlog_cil_push_pcp_aggregate fs/xfs/xfs_log_cil.c:137 [inline]
BUG: KASAN: slab-use-after-free in xlog_cil_push_work+0x986/0x2a90 fs/xfs/xfs_log_cil.c:1417
Write of size 8 at addr ffff888036db9c40 by task kworker/
Write of size 8 at addr ffff888036db9c40 by task kworker/u8:7/300

CPU: 0 UID: 0 PID: 300 Comm: kworker/u8:7 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: xfs-cil/loop4 xlog_cil_push_work
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
 __list_splice include/linux/list.h:577 [inline]
 list_splice_init include/linux/list.h:619 [inline]
 xlog_cil_push_pcp_aggregate fs/xfs/xfs_log_cil.c:137 [inline]
 xlog_cil_push_work+0x986/0x2a90 fs/xfs/xfs_log_cil.c:1417
 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/0x470 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
 </TASK>

Allocated by task 6232:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4683 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 kmem_cache_alloc_noprof+0x360/0x690 mm/slub.c:5010
 xfs_buf_item_init+0x6a/0x6e0 fs/xfs/xfs_buf_item.c:872
 _xfs_trans_bjoin+0x46/0x110 fs/xfs/xfs_trans_buf.c:75
 __xfs_trans_getsb+0x65/0x4a0 fs/xfs/xfs_trans_buf.c:191
 xfs_log_sb+0x43/0x200 fs/xfs/libxfs/xfs_sb.c:1327
 xfs_sync_sb_buf+0xc2/0x290 fs/xfs/libxfs/xfs_sb.c:1479
 xfs_ioc_setlabel+0x1d7/0x340 fs/xfs/xfs_ioctl.c:1081
 xfs_file_ioctl+0x901/0x1590 fs/xfs/xfs_ioctl.c:1238
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/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 6232:
 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:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2748 [inline]
 slab_free mm/slub.c:6508 [inline]
 kmem_cache_free+0x187/0x6d0 mm/slub.c:6635
 xfs_buf_ioend+0x235/0x790 fs/xfs/xfs_buf.c:1167
 xfs_buf_iowait+0x133/0x420 fs/xfs/xfs_buf.c:1336
 xfs_bwrite+0x5f/0xe0 fs/xfs/xfs_buf.c:1239
 xfs_sync_sb_buf+0x172/0x290 fs/xfs/libxfs/xfs_sb.c:1489
 xfs_ioc_setlabel+0x1d7/0x340 fs/xfs/xfs_ioctl.c:1081
 xfs_file_ioctl+0x901/0x1590 fs/xfs/xfs_ioctl.c:1238
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/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 ffff888036db9bd0
 which belongs to the cache xfs_buf_item of size 272
The buggy address is located 112 bytes inside of
 freed 272-byte region [ffff888036db9bd0, ffff888036db9ce0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36db9
flags: 0x80000000000000(node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000000 ffff888140431b40 dead000000000122 0000000000000000
raw: 0000000000000000 00000002000c000c 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 0xd2c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6225, tgid 6224 (syz.1.41), ts 236912521041
 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+0x2591/0x2600 mm/page_alloc.c:3943
 __alloc_frozen_pages_noprof+0x230/0x5c0 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+0x2d8/0x350 mm/slub.c:7417
 refill_sheaf mm/slub.c:2885 [inline]
 __pcs_replace_empty_main+0x339/0x690 mm/slub.c:4774
 alloc_from_pcs mm/slub.c:4850 [inline]
 slab_alloc_node mm/slub.c:4984 [inline]
 kmem_cache_alloc_noprof+0x45d/0x690 mm/slub.c:5010
 xfs_buf_item_init+0x6a/0x6e0 fs/xfs/xfs_buf_item.c:872
 _xfs_trans_bjoin+0x46/0x110 fs/xfs/xfs_trans_buf.c:75
 __xfs_trans_getsb+0x65/0x4a0 fs/xfs/xfs_trans_buf.c:191
 xfs_log_sb+0x43/0x200 fs/xfs/libxfs/xfs_sb.c:1327
 xfs_sync_sb_buf+0xc2/0x290 fs/xfs/libxfs/xfs_sb.c:1479
 xfs_ioc_setlabel+0x1d7/0x340 fs/xfs/xfs_ioctl.c:1081
 xfs_file_ioctl+0x901/0x1590 fs/xfs/xfs_ioctl.c:1238
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xff/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
page last free pid 6225 tgid 6224 ts 236910553419 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1418 [inline]
 __free_frozen_pages+0xf8e/0x1070 mm/page_alloc.c:2962
 __slab_free+0x250/0x2a0 mm/slub.c:5823
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4683 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 kmem_cache_alloc_noprof+0x360/0x690 mm/slub.c:5010
 alloc_filename fs/namei.c:147 [inline]
 do_getname+0x2e/0x250 fs/namei.c:187
 class_filename_flags_constructor include/linux/fs.h:2586 [inline]
 do_sys_openat2+0xcc/0x200 fs/open.c:1416
 do_sys_open fs/open.c:1423 [inline]
 __do_sys_openat fs/open.c:1439 [inline]
 __se_sys_openat fs/open.c:1434 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1434
 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

Memory state around the buggy address:
 ffff888036db9b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888036db9b80: 00 00 fc fc fc fc fc fc fc fc fa fb fb fb fb fb
>ffff888036db9c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888036db9c80: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff888036db9d00: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/26 01:31 upstream aa98230e410f f281d9d2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2 (corrupt fs)] ci2-upstream-fs KASAN: slab-use-after-free Write in xlog_cil_push_work
2026/09/26 01:31 upstream aa98230e410f f281d9d2 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-upstream-fs KASAN: slab-use-after-free Write in xlog_cil_push_work
2026/09/25 23:34 upstream aa98230e410f f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Write in xlog_cil_push_work
2026/09/25 23:31 upstream aa98230e410f f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Write in xlog_cil_push_work
2026/09/17 13:59 upstream 238650ef6c7c 95928915 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Write in xlog_cil_push_work
2026/09/25 23:26 upstream aa98230e410f f281d9d2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in xlog_cil_push_work
* Struck through repros no longer work on HEAD.