[v5.15] KASAN: use-after-free Read in lockref_put_or_lock (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c86c4726e7f0 Linux 5.15.211
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1195d8b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6f8e2266b61925dc
dashboard link: https://syzkaller.appspot.com/bug?extid=34b875840e0e70ee9ca5
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c3e980557785/disk-c86c4726.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5fbaf3714ad0/vmlinux-c86c4726.xz
kernel image: https://storage.googleapis.com/syzbot-assets/de60a4f1e940/bzImage-c86c4726.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+34b875...@syzkaller.appspotmail.com

RBP: 00007fff483a4910 R08: 00007fff483a5910 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff483a59a0
R13: 00007efc8e9212ca R14: 0000000000011b66 R15: 00007fff483a59e0
</TASK>
==================================================================
BUG: KASAN: use-after-free in __lock_acquire+0x107/0x7b50 kernel/locking/lockdep.c:4882
Read of size 8 at addr ffff88805df78048 by task syz-executor/4195

CPU: 1 PID: 4195 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
print_address_description+0x60/0x2d0 mm/kasan/report.c:248
__kasan_report mm/kasan/report.c:434 [inline]
kasan_report+0xdf/0x130 mm/kasan/report.c:451
__lock_acquire+0x107/0x7b50 kernel/locking/lockdep.c:4882
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:364 [inline]
lockref_put_or_lock+0x22/0xb0 lib/lockref.c:173
qd_put fs/gfs2/quota.c:309 [inline]
qd_unlock+0x195/0x2d0 fs/gfs2/quota.c:502
gfs2_quota_sync+0x63b/0x780 fs/gfs2/quota.c:1336
gfs2_sync_fs+0x48/0xb0 fs/gfs2/super.c:651
sync_filesystem+0xe6/0x220 fs/sync.c:56
generic_shutdown_super+0x6b/0x300 fs/super.c:448
kill_block_super+0x7c/0xe0 fs/super.c:1427
deactivate_locked_super+0x93/0xf0 fs/super.c:335
cleanup_mnt+0x426/0x4d0 fs/namespace.c:1148
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7efc8e88d097
Code: a2 c7 05 5c 26 25 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007fff483a4858 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007efc8e9212ca RCX: 00007efc8e88d097
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007fff483a4910
RBP: 00007fff483a4910 R08: 00007fff483a5910 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fff483a59a0
R13: 00007efc8e9212ca R14: 0000000000011b66 R15: 00007fff483a59e0
</TASK>

Allocated by task 4396:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track mm/kasan/common.c:46 [inline]
set_alloc_info mm/kasan/common.c:434 [inline]
__kasan_slab_alloc+0x92/0xc0 mm/kasan/common.c:467
kasan_slab_alloc include/linux/kasan.h:254 [inline]
slab_post_alloc_hook+0x4c/0x380 mm/slab.h:519
slab_alloc_node mm/slub.c:3225 [inline]
slab_alloc mm/slub.c:3233 [inline]
kmem_cache_alloc+0x15d/0x280 mm/slub.c:3238
kmem_cache_zalloc include/linux/slab.h:728 [inline]
qd_alloc+0x50/0x260 fs/gfs2/quota.c:216
gfs2_quota_init+0x74d/0xe80 fs/gfs2/quota.c:1426
gfs2_make_fs_rw+0x41c/0x590 fs/gfs2/super.c:159
gfs2_fill_super+0x17d1/0x1ea0 fs/gfs2/ops_fstype.c:1276
get_tree_bdev+0x3e6/0x610 fs/super.c:1325
gfs2_get_tree+0x4d/0x1e0 fs/gfs2/ops_fstype.c:1332
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x247/0xa40 fs/namespace.c:3034
do_mount fs/namespace.c:3377 [inline]
__do_sys_mount fs/namespace.c:3585 [inline]
__se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

Freed by task 20:
kasan_save_stack mm/kasan/common.c:38 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:46
kasan_set_free_info+0x1f/0x40 mm/kasan/generic.c:360
____kasan_slab_free+0xd5/0x110 mm/kasan/common.c:366
kasan_slab_free include/linux/kasan.h:230 [inline]
slab_free_hook mm/slub.c:1710 [inline]
slab_free_freelist_hook+0xec/0x170 mm/slub.c:1736
slab_free mm/slub.c:3504 [inline]
kmem_cache_free+0x8f/0x210 mm/slub.c:3520
rcu_do_batch kernel/rcu/tree.c:2523 [inline]
rcu_core+0x96e/0x1650 kernel/rcu/tree.c:2763
handle_softirqs+0x336/0x830 kernel/softirq.c:576
run_ksoftirqd+0xa4/0x100 kernel/softirq.c:943
smpboot_thread_fn+0x520/0x990 kernel/smpboot.c:164
kthread+0x42e/0x520 kernel/kthread.c:334
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Last potentially related work creation:
kasan_save_stack+0x35/0x60 mm/kasan/common.c:38
kasan_record_aux_stack+0xb8/0x100 mm/kasan/generic.c:348
__call_rcu kernel/rcu/tree.c:3011 [inline]
call_rcu+0x189/0x900 kernel/rcu/tree.c:3091
gfs2_quota_cleanup+0x414/0x670 fs/gfs2/quota.c:1490
gfs2_make_fs_ro+0x440/0x620 fs/gfs2/super.c:561
signal_our_withdraw fs/gfs2/util.c:166 [inline]
gfs2_withdraw+0x660/0x14e0 fs/gfs2/util.c:335
gfs2_dinode_in fs/gfs2/glops.c:-1 [inline]
gfs2_inode_refresh+0xb2d/0x11a0 fs/gfs2/glops.c:497
inode_go_lock+0x127/0x450 fs/gfs2/glops.c:522
do_promote+0x75b/0xb20 fs/gfs2/glock.c:507
finish_xmote+0x4c2/0xaf0 fs/gfs2/glock.c:678
do_xmote+0x752/0x10a0 fs/gfs2/glock.c:824
gfs2_glock_nq+0xc6b/0x1510 fs/gfs2/glock.c:1534
gfs2_glock_nq_init fs/gfs2/glock.h:246 [inline]
do_sync+0x49c/0xba0 fs/gfs2/quota.c:927
gfs2_quota_sync+0x355/0x780 fs/gfs2/quota.c:1329
gfs2_sync_fs+0x48/0xb0 fs/gfs2/super.c:651
sync_filesystem+0xe6/0x220 fs/sync.c:56
generic_shutdown_super+0x6b/0x300 fs/super.c:448
kill_block_super+0x7c/0xe0 fs/super.c:1427
deactivate_locked_super+0x93/0xf0 fs/super.c:335
cleanup_mnt+0x426/0x4d0 fs/namespace.c:1148
task_work_run+0x125/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0

The buggy address belongs to the object at ffff88805df78000
which belongs to the cache gfs2_quotad of size 272
The buggy address is located 72 bytes inside of
272-byte region [ffff88805df78000, ffff88805df78110)
The buggy address belongs to the page:
page:ffffea000177de00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5df78
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 0000000000000000 dead000000000122 ffff88801e1c1500
raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Reclaimable, gfp_mask 0x112c50(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL|__GFP_RECLAIMABLE), pid 4396, ts 72406602533, free_ts 23425417957
prep_new_page mm/page_alloc.c:2426 [inline]
get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
__alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
alloc_slab_page mm/slub.c:1780 [inline]
allocate_slab mm/slub.c:1917 [inline]
new_slab+0xc0/0x4b0 mm/slub.c:1980
___slab_alloc+0x807/0xdd0 mm/slub.c:3013
__slab_alloc mm/slub.c:3100 [inline]
slab_alloc_node mm/slub.c:3191 [inline]
slab_alloc mm/slub.c:3233 [inline]
kmem_cache_alloc+0xf0/0x280 mm/slub.c:3238
kmem_cache_zalloc include/linux/slab.h:728 [inline]
qd_alloc+0x50/0x260 fs/gfs2/quota.c:216
gfs2_quota_init+0x74d/0xe80 fs/gfs2/quota.c:1426
gfs2_make_fs_rw+0x41c/0x590 fs/gfs2/super.c:159
gfs2_fill_super+0x17d1/0x1ea0 fs/gfs2/ops_fstype.c:1276
get_tree_bdev+0x3e6/0x610 fs/super.c:1325
gfs2_get_tree+0x4d/0x1e0 fs/gfs2/ops_fstype.c:1332
vfs_get_tree+0x88/0x270 fs/super.c:1530
do_new_mount+0x247/0xa40 fs/namespace.c:3034
do_mount fs/namespace.c:3377 [inline]
__do_sys_mount fs/namespace.c:3585 [inline]
__se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1340 [inline]
free_pcp_prepare mm/page_alloc.c:1391 [inline]
free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
free_unref_page+0x8f/0x2a0 mm/page_alloc.c:3396
free_contig_range+0x96/0xf0 mm/page_alloc.c:9428
destroy_args+0xef/0xa00 mm/debug_vm_pgtable.c:1018
debug_vm_pgtable+0x321/0x380 mm/debug_vm_pgtable.c:1336
do_one_initcall+0x272/0x730 init/main.c:1315
do_initcall_level+0x13d/0x1f0 init/main.c:1388
do_initcalls+0x4b/0x90 init/main.c:1404
kernel_init_freeable+0x3d5/0x560 init/main.c:1628
kernel_init+0x19/0x1b0 init/main.c:1519
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Memory state around the buggy address:
ffff88805df77f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88805df77f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88805df78000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88805df78080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88805df78100: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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