syzbot
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: 177d, last: 23h39m
Sample crash report:
gfs2: fsid=syz:syz.0: jid=0, already locked for use
gfs2: fsid=syz:syz.0: jid=0: Looking at journal...
gfs2: fsid=syz:syz.0: jid=0: Journal head lookup took 113ms
gfs2: fsid=syz:syz.0: jid=0: Done
gfs2: fsid=syz:syz.0: fatal: invalid metadata block - bh = 9381 (bad magic number), function = gfs2_meta_buffer, file = fs/gfs2/meta_io.c, line = 460
loop0: writeback error on inode 9394, offset 3456000, sector 25590
==================================================================
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 ffff888051dd7920 by task kworker/0:6/5312
CPU: 0 UID: 0 PID: 5312 Comm: kworker/0:6 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
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:132 [inline]
__list_del_entry include/linux/list.h:246 [inline]
list_del_init include/linux/list.h:318 [inline]
gfs2_remove_from_ail fs/gfs2/log.c:79 [inline]
gfs2_ail_empty_tr fs/gfs2/log.c:287 [inline]
gfs2_ail_drain+0x1be/0xb20 fs/gfs2/log.c:946
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:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 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 5326:
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:4612 [inline]
slab_alloc_node mm/slub.c:4945 [inline]
kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4959
gfs2_glock_get+0x276/0xf20 fs/gfs2/glock.c:1098
gfs2_create_inode+0xdc6/0x1710 fs/gfs2/inode.c:835
gfs2_mkdir+0x9f/0xd0 fs/gfs2/inode.c:1354
vfs_mkdir+0x406/0x620 fs/namei.c:5276
filename_mkdirat+0x285/0x510 fs/namei.c:5309
__do_sys_mkdirat fs/namei.c:5330 [inline]
__se_sys_mkdirat+0x35/0x150 fs/namei.c:5327
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 15:
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:2705 [inline]
slab_free mm/slub.c:6405 [inline]
kmem_cache_free+0x182/0x650 mm/slub.c:6532
rcu_do_batch kernel/rcu/tree.c:2645 [inline]
rcu_core+0x78b/0x10a0 kernel/rcu/tree.c:2897
handle_softirqs+0x225/0x840 kernel/softirq.c:622
run_ksoftirqd+0x36/0x60 kernel/softirq.c:1076
smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
kthread+0x388/0x470 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
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:3159 [inline]
call_rcu+0xee/0x8b0 kernel/rcu/tree.c:3279
gfs2_glock_free+0x3c/0xa0 fs/gfs2/glock.c:152
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 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
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:2226
__queue_work+0xcd8/0x10a0 kernel/workqueue.c:2401
queue_delayed_work_on+0x11a/0x1e0 kernel/workqueue.c:2620
queue_delayed_work include/linux/workqueue.h:714 [inline]
gfs2_glock_queue_work fs/gfs2/glock.c:224 [inline]
do_xmote+0x539/0x770 fs/gfs2/glock.c:745
glock_work_func+0x2ef/0x600 fs/gfs2/glock.c:1011
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 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
The buggy address belongs to the object at ffff888051dd7808
which belongs to the cache gfs2_glock(aspace) of size 1176
The buggy address is located 280 bytes inside of
freed 1176-byte region [ffff888051dd7808, ffff888051dd7ca0)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x51dd4
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x4fff00000000040(head|node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000040 ffff888032930780 dead000000000122 0000000000000000
raw: 0000000000000000 00000008000c000c 00000000f5000000 0000000000000000
head: 04fff00000000040 ffff888032930780 dead000000000122 0000000000000000
head: 0000000000000000 00000008000c000c 00000000f5000000 0000000000000000
head: 04fff00000000002 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 5326, tgid 5324 (syz.0.0), ts 95426675721, free_ts 95336666030
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0x21fa/0x2270 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3294 [inline]
allocate_slab+0x79/0x5e0 mm/slub.c:3408
new_slab mm/slub.c:3454 [inline]
refill_objects+0x2d5/0x350 mm/slub.c:7338
refill_sheaf mm/slub.c:2832 [inline]
__pcs_replace_empty_main+0x2bf/0x6b0 mm/slub.c:4703
alloc_from_pcs mm/slub.c:4801 [inline]
slab_alloc_node mm/slub.c:4933 [inline]
kmem_cache_alloc_noprof+0x382/0x5f0 mm/slub.c:4959
gfs2_glock_get+0x276/0xf20 fs/gfs2/glock.c:1098
gfs2_create_inode+0xdc6/0x1710 fs/gfs2/inode.c:835
gfs2_mkdir+0x9f/0xd0 fs/gfs2/inode.c:1354
vfs_mkdir+0x406/0x620 fs/namei.c:5276
filename_mkdirat+0x285/0x510 fs/namei.c:5309
__do_sys_mkdirat fs/namei.c:5330 [inline]
__se_sys_mkdirat+0x35/0x150 fs/namei.c:5327
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 4701 tgid 4701 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xc1e/0xd10 mm/page_alloc.c:2950
__slab_free+0x274/0x2c0 mm/slub.c:5767
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:4612 [inline]
slab_alloc_node mm/slub.c:4945 [inline]
kmem_cache_alloc_noprof+0x2a0/0x5f0 mm/slub.c:4959
alloc_filename fs/namei.c:147 [inline]
do_getname+0x2e/0x250 fs/namei.c:187
class_filename_flags_constructor include/linux/fs.h:2566 [inline]
do_sys_openat2+0xcc/0x200 fs/open.c:1367
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1385
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff888051dd7800: fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888051dd7880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888051dd7900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888051dd7980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888051dd7a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
* Struck through repros no longer work on HEAD.