syzbot


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

Status: upstream: reported C repro on 2026/02/14 19:58
Subsystems: xfs
[Documentation on labels]
Reported-by: syzbot+fbf6ff30de890ff32ec5@syzkaller.appspotmail.com
First crash: 9d15h, last: 6h31m
Cause bisection: failed (error log, bisect log)
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [xfs?] KASAN: slab-use-after-free Read in fserror_worker 0 (1) 2026/02/14 19:58

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in inode_state_read_once include/linux/fs.h:884 [inline]
BUG: KASAN: slab-use-after-free in iput+0x3a7/0xe80 fs/inode.c:1977
Read of size 4 at addr ffff88805ab10ba8 by task kworker/1:1/36

CPU: 1 UID: 0 PID: 36 Comm: kworker/1:1 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Workqueue: events fserror_worker
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 inode_state_read_once include/linux/fs.h:884 [inline]
 iput+0x3a7/0xe80 fs/inode.c:1977
 fserror_worker+0x230/0x350 fs/fserror.c:69
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 6514:
 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:4459 [inline]
 slab_alloc_node mm/slub.c:4788 [inline]
 kmem_cache_alloc_lru_noprof+0x33c/0x680 mm/slub.c:4807
 xfs_inode_alloc+0x7e/0x670 fs/xfs/xfs_icache.c:97
 xfs_iget_cache_miss fs/xfs/xfs_icache.c:635 [inline]
 xfs_iget+0xa6b/0x2cb0 fs/xfs/xfs_icache.c:799
 xfs_lookup+0x321/0x630 fs/xfs/xfs_inode.c:553
 xfs_vn_lookup+0x130/0x200 fs/xfs/xfs_iops.c:327
 lookup_open fs/namei.c:4456 [inline]
 open_last_lookups fs/namei.c:4583 [inline]
 path_openat+0x11cb/0x38a0 fs/namei.c:4827
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 28:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 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:2670 [inline]
 slab_free mm/slub.c:6082 [inline]
 kmem_cache_free+0x185/0x690 mm/slub.c:6212
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core kernel/rcu/tree.c:2869 [inline]
 rcu_cpu_kthread+0x99e/0x1470 kernel/rcu/tree.c:2957
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3131 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3251
 xfs_iget_cache_miss fs/xfs/xfs_icache.c:740 [inline]
 xfs_iget+0xae5/0x2cb0 fs/xfs/xfs_icache.c:799
 xfs_lookup+0x321/0x630 fs/xfs/xfs_inode.c:553
 xfs_vn_lookup+0x130/0x200 fs/xfs/xfs_iops.c:327
 lookup_open fs/namei.c:4456 [inline]
 open_last_lookups fs/namei.c:4583 [inline]
 path_openat+0x11cb/0x38a0 fs/namei.c:4827
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88805ab10880
 which belongs to the cache xfs_inode of size 2032
The buggy address is located 808 bytes inside of
 freed 2032-byte region [ffff88805ab10880, ffff88805ab11070)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5ab10
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88805ab17f81
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff888140433a00 dead000000000100 dead000000000122
raw: 0000000000000000 00000008000f000f 00000000f5000000 ffff88805ab17f81
head: 0080000000000040 ffff888140433a00 dead000000000100 dead000000000122
head: 0000000000000000 00000008000f000f 00000000f5000000 ffff88805ab17f81
head: 0080000000000003 ffffea00016ac401 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Reclaimable, gfp_mask 0xd2050(__GFP_RECLAIMABLE|__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6067, tgid 6067 (syz.0.19), ts 110812692613, free_ts 91691246935
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3950
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5245
 alloc_slab_page mm/slub.c:3238 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3411
 new_slab mm/slub.c:3469 [inline]
 refill_objects+0x334/0x3c0 mm/slub.c:7091
 refill_sheaf mm/slub.c:2787 [inline]
 __pcs_replace_empty_main+0x328/0x5f0 mm/slub.c:4536
 alloc_from_pcs mm/slub.c:4639 [inline]
 slab_alloc_node mm/slub.c:4773 [inline]
 kmem_cache_alloc_lru_noprof+0x433/0x680 mm/slub.c:4807
 xfs_inode_alloc+0x7e/0x670 fs/xfs/xfs_icache.c:97
 xfs_iget_cache_miss fs/xfs/xfs_icache.c:635 [inline]
 xfs_iget+0xa6b/0x2cb0 fs/xfs/xfs_icache.c:799
 xfs_trans_metafile_iget+0x77/0x330 fs/xfs/xfs_icache.c:845
 xfs_rtginode_load+0x37c/0x8d0 fs/xfs/libxfs/xfs_rtgroup.c:469
 xfs_rtmount_rtg fs/xfs/xfs_rtalloc.c:1646 [inline]
 xfs_rtmount_inodes+0x247/0x7a0 fs/xfs/xfs_rtalloc.c:1683
 xfs_mountfs+0x11fb/0x22e0 fs/xfs/xfs_mount.c:1097
 xfs_fs_fill_super+0x11b5/0x1600 fs/xfs/xfs_super.c:1947
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
page last free pid 5848 tgid 5848 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1433 [inline]
 __free_frozen_pages+0xfd0/0x1160 mm/page_alloc.c:2973
 vfree+0x2ac/0x470 mm/vmalloc.c:3466
 kcov_put kernel/kcov.c:442 [inline]
 kcov_close+0x2e/0x60 kernel/kcov.c:543
 __fput+0x45e/0xa80 fs/file_table.c:469
 task_work_run+0x1d9/0x270 kernel/task_work.c:233
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x69b/0x2320 kernel/exit.c:971
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
 get_signal+0x125c/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88805ab10a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805ab10b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805ab10b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff88805ab10c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805ab10c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (26):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/15 08:41 upstream c22e26bd0906 1e62d198 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (corrupt fs)] [mounted in repro #2] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/11 06:59 upstream dc855b77719f 441e25b7 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/11 10:03 upstream dc855b77719f 441e25b7 .config console log report syz / log [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 Read in fserror_worker
2026/02/20 04:24 upstream 8bf22c33e7a1 c8d8c52d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/18 22:15 upstream c22e26bd0906 77d4d919 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/18 12:54 upstream c22e26bd0906 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/18 11:12 upstream c22e26bd0906 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/18 07:35 upstream c22e26bd0906 39751c21 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/17 23:05 upstream c22e26bd0906 06ec4f7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/17 18:55 upstream c22e26bd0906 06ec4f7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/17 05:28 upstream c22e26bd0906 e439b951 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/17 02:18 upstream c22e26bd0906 5d52cba5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/14 19:03 upstream c22e26bd0906 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/11 23:36 upstream 192c0159402e 75707236 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/10 20:19 upstream 72c395024dac 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/10 19:47 upstream 72c395024dac 91d776d3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: slab-use-after-free Read in fserror_worker
2026/02/19 13:31 upstream 956b9cbd7f15 746545b8 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/15 20:45 upstream ca4ee40bf13d 1e62d198 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/15 18:11 upstream ca4ee40bf13d 1e62d198 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/14 18:03 upstream 770aaedb461a 1e62d198 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/14 10:49 upstream 770aaedb461a 1e62d198 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/14 03:23 upstream cee73b1e840c 1e62d198 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/13 22:11 upstream cee73b1e840c 1e62d198 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/13 12:18 upstream 7449f86bafcd 6a673c50 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/11 01:41 upstream dc855b77719f 441e25b7 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in fserror_worker
2026/02/20 04:12 linux-next 44982d352c33 17d780d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in fserror_worker
* Struck through repros no longer work on HEAD.