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

Status: moderation: reported on 2026/09/21 14:04
Subsystems: xfs
Labels: prio:normal
[Documentation on labels]
Reported-by: syzbot+08eb6a3e3d56ca828caf@syzkaller.appspotmail.com
First crash: 4d05h, last: 4d05h
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
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
▶ ▼ 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 509d 509d 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 246d 396d 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 835d 841d 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 133d 129d 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:580 [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+0x9b6/0x2a90 fs/xfs/xfs_log_cil.c:1417
Write of size 8 at addr ffff8880261d5d88 by task kworker/u8:9/1441

CPU: 0 UID: 0 PID: 1441 Comm: kworker/u8:9 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: xfs-cil/loop3 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:580 [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+0x9b6/0x2a90 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 5944:
 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 5944:
 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 ffff8880261d5d20
 which belongs to the cache xfs_buf_item of size 272
The buggy address is located 104 bytes inside of
 freed 272-byte region [ffff8880261d5d20, ffff8880261d5e30)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x261d5
flags: 0x80000000000000(node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000000 ffff88814043fdc0 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 5795, tgid 5794 (syz.3.4), ts 106215173769
 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_read_buf_map+0x2ee/0x820 fs/xfs/xfs_trans_buf.c:294
 xfs_trans_read_buf fs/xfs/xfs_trans.h:212 [inline]
 xfs_read_icluster+0x218/0x3e0 fs/xfs/libxfs/xfs_inode_buf.c:139
 xfs_iget_cache_miss fs/xfs/xfs_icache.c:663 [inline]
 xfs_iget+0xc34/0x2f00 fs/xfs/xfs_icache.c:804
 xfs_trans_metafile_iget+0x77/0x330 fs/xfs/xfs_icache.c:853
 xfs_rtginode_load+0x3a3/0x920 fs/xfs/libxfs/xfs_rtgroup.c:469
 xfs_rtmount_rtg fs/xfs/xfs_rtalloc.c:1684 [inline]
 xfs_rtmount_inodes+0x14f/0x7a0 fs/xfs/xfs_rtalloc.c:1721
 xfs_mountfs+0x1254/0x2380 fs/xfs/xfs_mount.c:1095
page last free pid 5581 tgid 5581 ts 106036434714 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]
 __do_kmalloc_node mm/slub.c:5413 [inline]
 __kmalloc_node_track_caller_noprof+0x505/0x7b0 mm/slub.c:5545
 memdup_user+0x2b/0xd0 mm/util.c:221
 strndup_user+0x68/0xd0 mm/util.c:280
 copy_mount_string fs/namespace.c:4076 [inline]
 __do_sys_mount fs/namespace.c:4387 [inline]
 __se_sys_mount+0xdf/0x420 fs/namespace.c:4374
 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:
 ffff8880261d5c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880261d5d00: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
>ffff8880261d5d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff8880261d5e00: fb fb fb fb fb fb fc fc fc fc fc fc fc fc 00 00
 ffff8880261d5e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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
* Struck through repros no longer work on HEAD.