[moderation] [btrfs?] KASAN: slab-use-after-free Read in add_delayed_ref (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 54e82e93ca93 Merge tag 'core_urgent_for_v6.19_rc4' of git:..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1354c522580000
kernel config: https://syzkaller.appspot.com/x/.config?x=513255d80ab78f2b
dashboard link: https://syzkaller.appspot.com/bug?extid=57896778dbeb96b56b68
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
CC: [c...@fb.com dst...@suse.com jo...@toxicpanda.com linux...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-54e82e93.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f3befb5f53a4/vmlinux-54e82e93.xz
kernel image: https://storage.googleapis.com/syzbot-assets/92820ca1dbd8/bzImage-54e82e93.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+578967...@syzkaller.appspotmail.com

BTRFS info (device loop0): balance: start -d -m
BTRFS info (device loop0): relocating block group 6881280 flags data|metadata
BTRFS info (device loop0): found 2 extents, stage: move data extents
BTRFS info (device loop0): found 1 extents, stage: update data pointers
BTRFS info (device loop0): relocating block group 5242880 flags data|metadata
==================================================================
BUG: KASAN: slab-use-after-free in do_perf_trace_btrfs_delayed_tree_ref include/trace/events/btrfs.h:850 [inline]
BUG: KASAN: slab-use-after-free in perf_trace_btrfs_delayed_tree_ref+0x299/0x590 include/trace/events/btrfs.h:850
Read of size 8 at addr ffff888040ef94f8 by task syz.0.0/5342

CPU: 0 UID: 0 PID: 5342 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
do_perf_trace_btrfs_delayed_tree_ref include/trace/events/btrfs.h:850 [inline]
perf_trace_btrfs_delayed_tree_ref+0x299/0x590 include/trace/events/btrfs.h:850
__do_trace_add_delayed_tree_ref include/trace/events/btrfs.h:891 [inline]
trace_add_delayed_tree_ref include/trace/events/btrfs.h:891 [inline]
add_delayed_ref+0x1d25/0x1e70 fs/btrfs/delayed-ref.c:1089
btrfs_free_tree_block+0x2b6/0xc00 fs/btrfs/extent-tree.c:3456
btrfs_force_cow_block+0xfeb/0x2410 fs/btrfs/ctree.c:566
btrfs_cow_block+0x3c4/0xa80 fs/btrfs/ctree.c:708
btrfs_search_slot+0xd23/0x2ce0 fs/btrfs/ctree.c:2130
relocate_cowonly_block fs/btrfs/relocation.c:2574 [inline]
relocate_tree_blocks+0x124e/0x1fa0 fs/btrfs/relocation.c:2634
relocate_block_group+0x76e/0xd70 fs/btrfs/relocation.c:3573
btrfs_relocate_block_group+0x6b6/0xc70 fs/btrfs/relocation.c:3966
btrfs_relocate_chunk+0x12f/0x5c0 fs/btrfs/volumes.c:3424
__btrfs_balance+0x18ff/0x24e0 fs/btrfs/volumes.c:4197
btrfs_balance+0xac2/0x11b0 fs/btrfs/volumes.c:4571
btrfs_ioctl_balance+0x3d3/0x610 fs/btrfs/ioctl.c:3525
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f632278f7c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6323659038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f63229e6090 RCX: 00007f632278f7c9
RDX: 0000200000000180 RSI: 00000000c4009420 RDI: 000000000000000b
RBP: 00007f6322813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f63229e6128 R14: 00007f63229e6090 R15: 00007fffee852978
</TASK>

Allocated by task 5342:
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:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_noprof+0x37d/0x710 mm/slub.c:5270
add_delayed_ref+0x118/0x1e70 fs/btrfs/delayed-ref.c:1017
btrfs_free_tree_block+0x2b6/0xc00 fs/btrfs/extent-tree.c:3456
btrfs_force_cow_block+0xfeb/0x2410 fs/btrfs/ctree.c:566
btrfs_cow_block+0x3c4/0xa80 fs/btrfs/ctree.c:708
btrfs_search_slot+0xd23/0x2ce0 fs/btrfs/ctree.c:2130
relocate_cowonly_block fs/btrfs/relocation.c:2574 [inline]
relocate_tree_blocks+0x124e/0x1fa0 fs/btrfs/relocation.c:2634
relocate_block_group+0x76e/0xd70 fs/btrfs/relocation.c:3573
btrfs_relocate_block_group+0x6b6/0xc70 fs/btrfs/relocation.c:3966
btrfs_relocate_chunk+0x12f/0x5c0 fs/btrfs/volumes.c:3424
__btrfs_balance+0x18ff/0x24e0 fs/btrfs/volumes.c:4197
btrfs_balance+0xac2/0x11b0 fs/btrfs/volumes.c:4571
btrfs_ioctl_balance+0x3d3/0x610 fs/btrfs/ioctl.c:3525
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 1046:
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:2540 [inline]
slab_free mm/slub.c:6670 [inline]
kmem_cache_free+0x197/0x620 mm/slub.c:6781
btrfs_run_delayed_refs_for_head fs/btrfs/extent-tree.c:1985 [inline]
__btrfs_run_delayed_refs+0x1803/0x3af0 fs/btrfs/extent-tree.c:2048
btrfs_run_delayed_refs+0xe6/0x3a0 fs/btrfs/extent-tree.c:2160
flush_space+0x28f/0xd20 fs/btrfs/space-info.c:-1
do_async_reclaim_metadata_space+0x11e/0x350 fs/btrfs/space-info.c:1185
btrfs_async_reclaim_metadata_space+0x89/0xe0 fs/btrfs/space-info.c:1252
process_one_work kernel/workqueue.c:3257 [inline]
process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

The buggy address belongs to the object at ffff888040ef94d0
which belongs to the cache btrfs_delayed_ref_node of size 112
The buggy address is located 40 bytes inside of
freed 112-byte region [ffff888040ef94d0, ffff888040ef9540)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x40ef9
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 04fff00000000000 ffff8880411738c0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080170017 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x52c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5342, tgid 5340 (syz.0.0), ts 87297097779, free_ts 39618639308
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x234/0x290 mm/page_alloc.c:1857
prep_new_page mm/page_alloc.c:1865 [inline]
get_page_from_freelist+0x24e0/0x2580 mm/page_alloc.c:3915
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
alloc_slab_page mm/slub.c:3075 [inline]
allocate_slab+0x86/0x3b0 mm/slub.c:3248
new_slab mm/slub.c:3302 [inline]
___slab_alloc+0xe53/0x1820 mm/slub.c:4656
__slab_alloc+0x65/0x100 mm/slub.c:4779
__slab_alloc_node mm/slub.c:4855 [inline]
slab_alloc_node mm/slub.c:5251 [inline]
kmem_cache_alloc_noprof+0x40f/0x710 mm/slub.c:5270
add_delayed_ref+0x118/0x1e70 fs/btrfs/delayed-ref.c:1017
btrfs_alloc_tree_block+0xcf8/0x1220 fs/btrfs/extent-tree.c:5208
btrfs_force_cow_block+0x578/0x2410 fs/btrfs/ctree.c:517
btrfs_cow_block+0x3c4/0xa80 fs/btrfs/ctree.c:708
btrfs_search_slot+0xd23/0x2ce0 fs/btrfs/ctree.c:2130
btrfs_update_root+0xea/0xea0 fs/btrfs/root-tree.c:144
commit_fs_roots+0x56a/0x9a0 fs/btrfs/transaction.c:1531
btrfs_commit_transaction+0x1014/0x3b10 fs/btrfs/transaction.c:2460
page last free pid 15 tgid 15 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0xbc8/0xd30 mm/page_alloc.c:2943
__tlb_remove_table_free mm/mmu_gather.c:227 [inline]
tlb_remove_table_rcu+0x85/0x100 mm/mmu_gather.c:290
rcu_do_batch kernel/rcu/tree.c:2605 [inline]
rcu_core+0xc8e/0x1720 kernel/rcu/tree.c:2857
handle_softirqs+0x22b/0x7c0 kernel/softirq.c:622
run_ksoftirqd+0x36/0x60 kernel/softirq.c:1063
smpboot_thread_fn+0x542/0xa60 kernel/smpboot.c:160
kthread+0x711/0x8a0 kernel/kthread.c:463
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Memory state around the buggy address:
ffff888040ef9380: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff888040ef9400: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
>ffff888040ef9480: fb fb fc fc fc fc fc fc fc fc fa fb fb fb fb fb
^
ffff888040ef9500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff888040ef9580: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
==================================================================


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