[moderation] [gfs2?] KASAN: slab-use-after-free Read in do_sync

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f09079bd04a9 Merge tag 'powerpc-6.16-2' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10d7260c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c07f08ee4bcfb276
dashboard link: https://syzkaller.appspot.com/bug?extid=0906e354f55610be5880
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [agru...@redhat.com gf...@lists.linux.dev linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b12c192d71be/disk-f09079bd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4a5f5364cde0/vmlinux-f09079bd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6cceaf0783ab/bzImage-f09079bd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+0906e3...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
Read of size 1 at addr ffff8880506fe198 by task syz-executor/5835

CPU: 0 UID: 0 PID: 5835 Comm: syz-executor Not tainted 6.16.0-rc1-syzkaller-00003-gf09079bd04a9 #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xd2/0x2b0 mm/kasan/report.c:521
kasan_report+0x118/0x150 mm/kasan/report.c:634
__kasan_check_byte+0x2a/0x40 mm/kasan/common.c:557
kasan_check_byte include/linux/kasan.h:399 [inline]
lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5845
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
do_sync+0xa79/0xc60 fs/gfs2/quota.c:986
gfs2_quota_sync+0x359/0x460 fs/gfs2/quota.c:1357
gfs2_sync_fs+0x4c/0xb0 fs/gfs2/super.c:660
sync_filesystem+0xee/0x230 fs/sync.c:56
generic_shutdown_super+0x6f/0x2c0 fs/super.c:622
kill_block_super+0x44/0x90 fs/super.c:1753
deactivate_locked_super+0xbc/0x130 fs/super.c:474
cleanup_mnt+0x425/0x4c0 fs/namespace.c:1417
task_work_run+0x1d4/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:114
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f038d58fc57
Code: a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 0f 1f 44 00 00 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 a8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffd2e813b28 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 00007f038d610925 RCX: 00007f038d58fc57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffd2e813be0
RBP: 00007ffd2e813be0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 00007ffd2e814c70
R13: 00007f038d610925 R14: 000000000007c36b R15: 00007ffd2e814cb0
</TASK>

Allocated by task 10371:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
unpoison_slab_object mm/kasan/common.c:319 [inline]
__kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:345
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4148 [inline]
slab_alloc_node mm/slub.c:4197 [inline]
kmem_cache_alloc_noprof+0x1c1/0x3c0 mm/slub.c:4204
qd_alloc+0x50/0x250 fs/gfs2/quota.c:234
gfs2_quota_init+0x777/0x1230 fs/gfs2/quota.c:1448
gfs2_make_fs_rw+0x181/0x2b0 fs/gfs2/super.c:149
gfs2_fill_super+0x1a91/0x20e0 fs/gfs2/ops_fstype.c:1278
get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1679
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1335
vfs_get_tree+0x92/0x2b0 fs/super.c:1802
do_new_mount+0x24a/0xa40 fs/namespace.c:3885
do_mount fs/namespace.c:4222 [inline]
__do_sys_mount fs/namespace.c:4433 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4410
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 1033:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2381 [inline]
slab_free mm/slub.c:4643 [inline]
kmem_cache_free+0x18f/0x400 mm/slub.c:4745
gfs2_qd_dealloc+0x70/0xe0 fs/gfs2/quota.c:111
rcu_do_batch kernel/rcu/tree.c:2576 [inline]
rcu_core+0xca8/0x1710 kernel/rcu/tree.c:2832
handle_softirqs+0x286/0x870 kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0xca/0x1f0 kernel/softirq.c:680
irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1050
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

Last potentially related work creation:
kasan_save_stack+0x3e/0x60 mm/kasan/common.c:47
kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:548
__call_rcu_common kernel/rcu/tree.c:3090 [inline]
call_rcu+0x142/0x990 kernel/rcu/tree.c:3210
gfs2_qd_list_dispose fs/gfs2/quota.c:146 [inline]
gfs2_qd_shrink_scan+0x281/0x330 fs/gfs2/quota.c:185
do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437
shrink_slab+0xd74/0x10d0 mm/shrinker.c:664
drop_slab_node mm/vmscan.c:442 [inline]
drop_slab+0x14e/0x290 mm/vmscan.c:460
drop_caches_sysctl_handler+0xc7/0x170 fs/drop_caches.c:68
proc_sys_call_handler+0x50c/0x7c0 fs/proc/proc_sysctl.c:601
iter_file_splice_write+0x93a/0x1000 fs/splice.c:738
do_splice_from fs/splice.c:935 [inline]
direct_splice_actor+0x101/0x160 fs/splice.c:1158
splice_direct_to_actor+0x5a8/0xcc0 fs/splice.c:1102
do_splice_direct_actor fs/splice.c:1201 [inline]
do_splice_direct+0x181/0x270 fs/splice.c:1227
do_sendfile+0x4da/0x7e0 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1425 [inline]
__se_sys_sendfile64+0xd9/0x190 fs/read_write.c:1417
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880506fe150
which belongs to the cache gfs2_quotad of size 272
The buggy address is located 72 bytes inside of
freed 272-byte region [ffff8880506fe150, ffff8880506fe260)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff8880506fe2a0 pfn:0x506fe
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88801fbe1a00 dead000000000122 0000000000000000
raw: ffff8880506fe2a0 00000000800c000a 00000000f5000000 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 0x52c50(GFP_NOFS|__GFP_RECLAIMABLE|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 6787, tgid 6786 (syz.5.194), ts 178953542870, free_ts 27266787671
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
prep_new_page mm/page_alloc.c:1712 [inline]
get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3669
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
alloc_slab_page mm/slub.c:2451 [inline]
allocate_slab+0x8a/0x3b0 mm/slub.c:2619
new_slab mm/slub.c:2673 [inline]
___slab_alloc+0xbfc/0x1480 mm/slub.c:3859
__slab_alloc mm/slub.c:3949 [inline]
__slab_alloc_node mm/slub.c:4024 [inline]
slab_alloc_node mm/slub.c:4185 [inline]
kmem_cache_alloc_noprof+0x283/0x3c0 mm/slub.c:4204
qd_alloc+0x50/0x250 fs/gfs2/quota.c:234
gfs2_quota_init+0x777/0x1230 fs/gfs2/quota.c:1448
gfs2_make_fs_rw+0x181/0x2b0 fs/gfs2/super.c:149
gfs2_fill_super+0x1a91/0x20e0 fs/gfs2/ops_fstype.c:1278
get_tree_bdev_flags+0x40e/0x4d0 fs/super.c:1679
gfs2_get_tree+0x51/0x1e0 fs/gfs2/ops_fstype.c:1335
vfs_get_tree+0x92/0x2b0 fs/super.c:1802
do_new_mount+0x24a/0xa40 fs/namespace.c:3885
do_mount fs/namespace.c:4222 [inline]
__do_sys_mount fs/namespace.c:4433 [inline]
__se_sys_mount+0x317/0x410 fs/namespace.c:4410
page last free pid 1 tgid 1 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1248 [inline]
__free_frozen_pages+0xc71/0xe70 mm/page_alloc.c:2706
__free_pages mm/page_alloc.c:5071 [inline]
free_contig_range+0x1bd/0x4a0 mm/page_alloc.c:6927
destroy_args+0x7e/0x5d0 mm/debug_vm_pgtable.c:1009
debug_vm_pgtable+0x412/0x450 mm/debug_vm_pgtable.c:1389
do_one_initcall+0x236/0x820 init/main.c:1273
do_initcall_level+0x137/0x1f0 init/main.c:1335
do_initcalls+0x69/0xd0 init/main.c:1351
kernel_init_freeable+0x3d9/0x570 init/main.c:1583
kernel_init+0x1d/0x1d0 init/main.c:1473
ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
ffff8880506fe080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880506fe100: fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb fb
>ffff8880506fe180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880506fe200: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff8880506fe280: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
==================================================================


---
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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.