KASAN: slab-use-after-free Read in gfs2_ail_drain

Status: upstream: reported on 2026/04/05 21:30
Subsystems: gfs2
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+84a21b16aba9f279d96a@syzkaller.appspotmail.com
First crash: 214d, last: 3d05h
▶ ▼ ✨ AI Jobs (4)
ID Workflow Result Correct Bug Created Started Finished Revision
083e3e32 assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KASAN: slab-use-after-free Read in gfs2_ail_drain 2026/06/01 08:09 2026/06/01 08:09 2026/06/01 09:09 6b4a8443
822a6f54 assessment-security 💥 KASAN: slab-use-after-free Read in gfs2_ail_drain 2026/05/15 10:39 2026/05/15 10:39 2026/05/15 10:40 9cd3beaa
6a5040ad repro ❓ KASAN: slab-use-after-free Read in gfs2_ail_drain 2026/03/07 13:07 2026/03/07 13:07 2026/03/07 13:17 31e9c887
2b286aba moderation Actionable: ✅ Confident: ✅ ❓ KASAN: slab-use-after-free Read in gfs2_ail_drain 2026/02/06 07:04 2026/02/06 08:33 2026/02/06 08:48 9b618abc
▶ ▼ Discussions (4)
Title Replies (including bot) Last reply
[syzbot] Monthly gfs2 report (Aug 2026) 0 (1) 2026/08/25 12:32
[syzbot] Monthly gfs2 report (Jul 2026) 0 (1) 2026/07/25 04:32
[PATCH] gfs2: keep LRU glocks with pending AIL during withdraw 1 (1) 2026/07/09 17:17
[syzbot] [gfs2?] KASAN: slab-use-after-free Read in gfs2_ail_drain 0 (1) 2026/04/05 21:30

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in __list_del_entry_valid_or_report+0x92/0x190 lib/list_debug.c:62
Read of size 8 at addr ffff888067fd5fa8 by task kworker/0:1/16524

CPU: 0 UID: 0 PID: 16524 Comm: kworker/0:1 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: events gfs2_withdraw_func
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_del_entry_valid_or_report+0x92/0x190 lib/list_debug.c:62
 __list_del_entry_valid include/linux/list.h:140 [inline]
 __list_del_entry include/linux/list.h:261 [inline]
 list_del_init include/linux/list.h:333 [inline]
 gfs2_remove_from_ail fs/gfs2/log.c:79 [inline]
 gfs2_ail_empty_tr fs/gfs2/log.c:287 [inline]
 gfs2_ail_drain+0x848/0xb20 fs/gfs2/log.c:954
 do_withdraw+0x10d/0x2f0 fs/gfs2/util.c:126
 gfs2_withdraw_func+0x2ef/0x440 fs/gfs2/util.c:-1
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
 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
 </TASK>

Allocated by task 8822:
 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+0x2b9/0x600 mm/slub.c:5010
 gfs2_glock_get+0x276/0xf20 fs/gfs2/glock.c:1074
 gfs2_inode_lookup+0x2a3/0xc30 fs/gfs2/inode.c:149
 gfs2_lookup_root fs/gfs2/ops_fstype.c:428 [inline]
 init_sb+0xa55/0x1300 fs/gfs2/ops_fstype.c:497
 gfs2_fill_super+0x1634/0x20d0 fs/gfs2/ops_fstype.c:1219
 get_tree_bdev_flags+0x430/0x4f0 fs/super.c:1887
 gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1333
 vfs_get_tree+0x92/0x2a0 fs/super.c:1947
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3848
 do_mount fs/namespace.c:4181 [inline]
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount+0x31d/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

Freed by task 29966:
 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:6499 [inline]
 kmem_cache_free+0x182/0x650 mm/slub.c:6626
 rcu_do_batch kernel/rcu/tree.c:2650 [inline]
 rcu_core+0x926/0x1260 kernel/rcu/tree.c:2919
 handle_softirqs+0x226/0x860 kernel/softirq.c:645
 do_softirq+0x77/0xd0 kernel/softirq.c:546
 __local_bh_enable_ip+0x100/0x140 kernel/softirq.c:473
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 __ip6_del_rt+0xa5/0x180 net/ipv6/route.c:3991
 ip6_del_rt+0xc3/0x120 net/ipv6/route.c:4005
 __ipv6_ifa_notify+0x897/0xc60 net/ipv6/addrconf.c:6347
 addrconf_ifdown+0xe7a/0x1a30 net/ipv6/addrconf.c:4013
 addrconf_notify+0x1bc/0x1050 net/ipv6/addrconf.c:-1
 notifier_call_chain+0x1a5/0x3d0 kernel/notifier.c:85
 call_netdevice_notifiers_extack net/core/dev.c:2313 [inline]
 call_netdevice_notifiers net/core/dev.c:2327 [inline]
 netif_close_many+0x463/0x660 net/core/dev.c:1829
 unregister_netdevice_many_notify+0xb76/0x2140 net/core/dev.c:12487
 ops_exit_rtnl_list net/core/net_namespace.c:188 [inline]
 ops_undo_list+0x391/0x8d0 net/core/net_namespace.c:249
 cleanup_net+0x572/0x810 net/core/net_namespace.c:706
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
 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

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:3181 [inline]
 call_rcu+0xee/0x8b0 kernel/rcu/tree.c:3301
 gfs2_glock_free+0x3c/0xa0 fs/gfs2/glock.c:150
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
 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

Second to 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
 insert_work+0x3d/0x330 kernel/workqueue.c:2272
 __queue_work+0xd07/0x10d0 kernel/workqueue.c:2448
 queue_delayed_work_on+0x11a/0x1e0 kernel/workqueue.c:2669
 queue_delayed_work include/linux/workqueue.h:715 [inline]
 gfs2_glock_queue_work fs/gfs2/glock.c:198 [inline]
 do_xmote+0x539/0x770 fs/gfs2/glock.c:718
 glock_work_func+0x30d/0x610 fs/gfs2/glock.c:987
 process_one_work kernel/workqueue.c:3387 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3470
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3551
 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

The buggy address belongs to the object at ffff888067fd5e90
 which belongs to the cache gfs2_glock(aspace) of size 1176
The buggy address is located 280 bytes inside of
 freed 1176-byte region [ffff888067fd5e90, ffff888067fd6328)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x67fd4
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801efef3c0 dead000000000100 dead000000000122
raw: 0000000000000000 00000002000c000c 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801efef3c0 dead000000000100 dead000000000122
head: 0000000000000000 00000002000c000c 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 29449, tgid 29447 (syz.9.5867), ts 1352109876835
 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:7410
 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]
 kmem_cache_alloc_noprof+0x399/0x600 mm/slub.c:5010
 gfs2_glock_get+0x276/0xf20 fs/gfs2/glock.c:1074
 gfs2_inode_lookup+0x2a3/0xc30 fs/gfs2/inode.c:149
 gfs2_lookup_root fs/gfs2/ops_fstype.c:428 [inline]
 init_sb+0xa55/0x1300 fs/gfs2/ops_fstype.c:497
 gfs2_fill_super+0x1634/0x20d0 fs/gfs2/ops_fstype.c:1219
 get_tree_bdev_flags+0x430/0x4f0 fs/super.c:1887
 gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1333
 vfs_get_tree+0x92/0x2a0 fs/super.c:1947
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3848
 do_mount fs/namespace.c:4181 [inline]
 __do_sys_mount fs/namespace.c:4397 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4374
page last free pid 29449 tgid 29447 ts 1352017514945 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
 stack_depot_save_flags+0x41e/0x7f0 lib/stackdepot.c:735
 kasan_save_stack mm/kasan/common.c:58 [inline]
 kasan_save_track+0x4f/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __do_kmalloc_node mm/slub.c:5414 [inline]
 __kmalloc_noprof+0x36b/0x720 mm/slub.c:5439
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 memcg_init_list_lru_one mm/list_lru.c:468 [inline]
 __memcg_list_lru_alloc+0x1d9/0x760 mm/list_lru.c:601
 __memcg_slab_post_alloc_hook+0x3bf/0xf80 mm/memcontrol.c:3632
 memcg_slab_post_alloc_hook mm/slub.c:2517 [inline]
 slab_post_alloc_hook mm/slub.c:4702 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 kmem_cache_alloc_lru_noprof+0x351/0x5f0 mm/slub.c:5029
 gfs2_alloc_inode+0x58/0x170 fs/gfs2/super.c:1520
 alloc_inode+0x6a/0x1b0 fs/inode.c:338
 new_inode+0x1f/0x170 fs/inode.c:1171
 gfs2_fill_super+0xd7a/0x20d0 fs/gfs2/ops_fstype.c:1172
 get_tree_bdev_flags+0x430/0x4f0 fs/super.c:1887
 gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1333
 vfs_get_tree+0x92/0x2a0 fs/super.c:1947
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3772 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3848

Memory state around the buggy address:
 ffff888067fd5e80: fc fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888067fd5f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888067fd5f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff888067fd6000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888067fd6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (24):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/28 13:01 upstream 1b78070aaef6 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/27 14:01 upstream 818bebeb63dd c53a1b9c .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/25 21:40 upstream 818bebeb63dd a9a1fc32 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/18 04:39 upstream ff68e5f557f6 1e72964b .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/15 20:30 upstream 15ef2f78c49d 746171ee .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/15 20:23 upstream 15ef2f78c49d 746171ee .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/14 13:37 upstream 2f1baf1fc892 2cf1fbb7 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/14 13:08 upstream 2f1baf1fc892 2cf1fbb7 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/11 04:28 upstream d58772d8520c 508909ea .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/11 04:18 upstream d58772d8520c 508909ea .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/07/26 18:08 upstream 3dab139d4795 492bab15 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/07/24 16:09 upstream 48a5a7ab8d6a dd737a83 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/07/22 15:29 upstream 248951ddc14d 4a865b71 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/07/14 07:34 upstream 0f26556c5eee 2130f682 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/05/23 09:33 upstream cca95436be15 c69befb3 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/05/06 14:42 upstream 74fe02ce122a 23ad3581 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/04/05 21:29 upstream 1791c390149f 4440e7c2 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/04/05 21:22 upstream 1791c390149f 4440e7c2 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/03/03 20:30 upstream af4e9ef3d784 4180d919 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/02/03 11:45 upstream 6bd9ed02871f 6df4c87a .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/01/29 06:04 upstream 8dfce8991b95 0adc945e .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/28 13:03 linux-next 3d83758432b5 e2fa417d .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/25 00:45 linux-next 4b18edbd8e70 23caa175 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in gfs2_ail_drain
2026/08/07 13:36 linux-next ea2bff00da89 e4ef95d6 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root KASAN: slab-use-after-free Read in gfs2_ail_drain
* Struck through repros no longer work on HEAD.