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Message-ID: <684a8704.a00a0220.1eb5f5.00fb.GAE@google.com>
Date: Thu, 12 Jun 2025 00:51:32 -0700
From: syzbot <syzbot+2887a13a5c387e616a68@...kaller.appspotmail.com>
To: kent.overstreet@...ux.dev, linux-bcachefs@...r.kernel.org,
linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: [syzbot] [bcachefs?] KASAN: slab-use-after-free Read in bch2_bucket_alloc_trans
Hello,
syzbot found the following issue on:
HEAD commit: 19a60293b992 Add linux-next specific files for 20250611
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15eb660c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=76ed3656d7159e27
dashboard link: https://syzkaller.appspot.com/bug?extid=2887a13a5c387e616a68
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=102f4e0c580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=178f460c580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c453c11565fa/disk-19a60293.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4034ded42b2e/vmlinux-19a60293.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5355903cdb8f/bzImage-19a60293.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/e4f3a815594e/mount_0.gz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2887a13a5c387e616a68@...kaller.appspotmail.com
need_inc_gen 0
dirty_sectors 256
stripe_sectors 0
cached_sectors 0
stripe 0
stripe_redundancy 0
io_time[READ] 0
io_time[WRITE] 0
fragmentation 0
bp_start 8
incorrectly set at freespace:0:30:0 (free 0, genbits 0 should be 0), fixing
==================================================================
BUG: KASAN: slab-use-after-free in bch2_bucket_alloc_trans+0x1aa0/0x2410 fs/bcachefs/alloc_foreground.c:547
Read of size 8 at addr ffff88802fe9fd20 by task kworker/u8:5/1153
CPU: 0 UID: 0 PID: 1153 Comm: kworker/u8:5 Not tainted 6.16.0-rc1-next-20250611-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: btree_node_rewrite async_btree_node_rewrite_work
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
bch2_bucket_alloc_trans+0x1aa0/0x2410 fs/bcachefs/alloc_foreground.c:547
bch2_bucket_alloc_set_trans+0x5a6/0xe70 fs/bcachefs/alloc_foreground.c:728
__open_bucket_add_buckets+0x1437/0x1e40 fs/bcachefs/alloc_foreground.c:925
open_bucket_add_buckets+0x2ee/0x440 fs/bcachefs/alloc_foreground.c:957
bch2_alloc_sectors_start_trans+0xd26/0x1e80 fs/bcachefs/alloc_foreground.c:-1
__bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:318 [inline]
bch2_btree_reserve_get+0x618/0x1510 fs/bcachefs/btree_update_interior.c:526
bch2_btree_update_start+0x147e/0x1dc0 fs/bcachefs/btree_update_interior.c:1261
bch2_btree_node_rewrite+0x17e/0x1120 fs/bcachefs/btree_update_interior.c:2236
bch2_btree_node_rewrite_key fs/bcachefs/btree_update_interior.c:2302 [inline]
async_btree_node_rewrite_work+0x370/0x840 fs/bcachefs/btree_update_interior.c:2359
process_one_work kernel/workqueue.c:3235 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3318
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3399
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Allocated by task 1153:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__do_kmalloc_node mm/slub.c:4328 [inline]
__kmalloc_node_track_caller_noprof+0x271/0x4e0 mm/slub.c:4347
__do_krealloc mm/slub.c:4905 [inline]
krealloc_noprof+0x124/0x340 mm/slub.c:4958
__bch2_trans_kmalloc+0x26c/0xc80 fs/bcachefs/btree_iter.c:3187
bch2_trans_kmalloc_nomemzero_ip fs/bcachefs/btree_iter.h:586 [inline]
bch2_trans_kmalloc_nomemzero fs/bcachefs/btree_iter.h:621 [inline]
bch2_alloc_sectors_start_trans+0x1d59/0x1e80 fs/bcachefs/alloc_foreground.c:1250
__bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:318 [inline]
bch2_btree_reserve_get+0x618/0x1510 fs/bcachefs/btree_update_interior.c:526
bch2_btree_update_start+0x147e/0x1dc0 fs/bcachefs/btree_update_interior.c:1261
bch2_btree_node_rewrite+0x17e/0x1120 fs/bcachefs/btree_update_interior.c:2236
bch2_btree_node_rewrite_key fs/bcachefs/btree_update_interior.c:2302 [inline]
async_btree_node_rewrite_work+0x370/0x840 fs/bcachefs/btree_update_interior.c:2359
process_one_work kernel/workqueue.c:3235 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3318
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3399
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Freed by task 1153:
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]
kfree+0x18e/0x440 mm/slub.c:4842
krealloc_noprof+0x1cd/0x340 mm/slub.c:-1
__bch2_trans_kmalloc+0x26c/0xc80 fs/bcachefs/btree_iter.c:3187
bch2_trans_kmalloc_nomemzero_ip fs/bcachefs/btree_iter.h:586 [inline]
bch2_trans_kmalloc_nomemzero fs/bcachefs/btree_iter.h:621 [inline]
__bch2_trans_subbuf_alloc+0x2da/0x460 fs/bcachefs/btree_update.c:557
bch2_trans_subbuf_alloc fs/bcachefs/btree_update.h:148 [inline]
bch2_trans_jset_entry_alloc fs/bcachefs/btree_update.h:168 [inline]
__bch2_trans_log_str fs/bcachefs/btree_update.c:814 [inline]
bch2_trans_log_str+0xd5/0x3c0 fs/bcachefs/btree_update.c:827
__bch2_fsck_err+0xc11/0xfb0 fs/bcachefs/error.c:625
bch2_check_discard_freespace_key+0x71b/0xce0 fs/bcachefs/alloc_background.c:1436
try_alloc_bucket fs/bcachefs/alloc_foreground.c:272 [inline]
bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:420 [inline]
bch2_bucket_alloc_trans+0x1333/0x2410 fs/bcachefs/alloc_foreground.c:544
bch2_bucket_alloc_set_trans+0x5a6/0xe70 fs/bcachefs/alloc_foreground.c:728
__open_bucket_add_buckets+0x1437/0x1e40 fs/bcachefs/alloc_foreground.c:925
open_bucket_add_buckets+0x2ee/0x440 fs/bcachefs/alloc_foreground.c:957
bch2_alloc_sectors_start_trans+0xd26/0x1e80 fs/bcachefs/alloc_foreground.c:-1
__bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:318 [inline]
bch2_btree_reserve_get+0x618/0x1510 fs/bcachefs/btree_update_interior.c:526
bch2_btree_update_start+0x147e/0x1dc0 fs/bcachefs/btree_update_interior.c:1261
bch2_btree_node_rewrite+0x17e/0x1120 fs/bcachefs/btree_update_interior.c:2236
bch2_btree_node_rewrite_key fs/bcachefs/btree_update_interior.c:2302 [inline]
async_btree_node_rewrite_work+0x370/0x840 fs/bcachefs/btree_update_interior.c:2359
process_one_work kernel/workqueue.c:3235 [inline]
process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3318
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3399
kthread+0x711/0x8a0 kernel/kthread.c:464
ret_from_fork+0x3f9/0x770 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
The buggy address belongs to the object at ffff88802fe9fc00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 288 bytes inside of
freed 512-byte region [ffff88802fe9fc00, ffff88802fe9fe00)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2fe9c
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801a441c80 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a441c80 0000000000000000 dead000000000001
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0000bfa701 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5210, tgid 5210 (udevd), ts 52772311742, free_ts 47887520110
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]
__kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4354
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
kernfs_fop_open+0x397/0xca0 fs/kernfs/file.c:623
do_dentry_open+0xdf3/0x1970 fs/open.c:964
vfs_open+0x3b/0x340 fs/open.c:1094
do_open fs/namei.c:3887 [inline]
path_openat+0x2ee5/0x3830 fs/namei.c:4046
do_filp_open+0x1fa/0x410 fs/namei.c:4073
do_sys_openat2+0x121/0x1c0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1463
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
page last free pid 5220 tgid 5220 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
__slab_free+0x326/0x400 mm/slub.c:4554
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:329
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
getname_flags+0xb8/0x540 fs/namei.c:146
getname include/linux/fs.h:2905 [inline]
do_sys_openat2+0xbc/0x1c0 fs/open.c:1431
do_sys_open fs/open.c:1452 [inline]
__do_sys_openat fs/open.c:1468 [inline]
__se_sys_openat fs/open.c:1463 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1463
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
Memory state around the buggy address:
ffff88802fe9fc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802fe9fc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802fe9fd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802fe9fd80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802fe9fe00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@...glegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
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