KASAN: global-out-of-bounds Read in rcu_pending_exit

Status: auto-obsoleted due to no activity on 2025/12/30 19:26
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+e733ab672a1b6724c27f@syzkaller.appspotmail.com
First crash: 631d, last: 325d
Cause bisection: introduced by (bisect log) :
commit d97de0d017cde0d442c3d144b4f969f43064cc0f
Author: Kent Overstreet <kent.overstreet@linux.dev>
Date: Tue Aug 13 01:31:25 2024 +0000

  bcachefs: Make bkey_fsck_err() a wrapper around fsck_err()

Crash: general protection fault in put_pwq_unlocked (log)
Repro: syz .config
  
Fix bisection: fixed by (bisect log) :
commit f2c61db29f277b9c80de92102fc532cc247495cd
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date: Mon Sep 29 20:43:52 2025 +0000

  Remove bcachefs core code

  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] KASAN: global-out-of-bounds Read in rcu_pending_exit 0 (5) 2025/10/23 07:46
▶ ▼ Last patch testing requests (8)
Created Duration User Patch Repo Result
2025/12/03 11:15 19m retest repro upstream no crash log
2025/08/31 10:35 24m retest repro upstream report log
2025/06/11 01:06 23m retest repro linux-next no crash log
2025/04/01 06:38 19m retest repro linux-next report log
2025/03/29 15:32 17m retest repro upstream report log
2025/03/06 18:56 27m retest repro upstream report log
2025/01/20 21:53 14m retest repro linux-next error
2025/01/04 03:04 16m retest repro upstream report log
▶ ▼ Fix bisection attempts (7)
Created Duration User Patch Repo Result
2025/10/22 22:21 9h24m bisect fix upstream OK (1) job log
2025/09/21 17:05 2h19m bisect fix upstream OK (0) job log log
2025/08/17 06:33 2h51m bisect fix upstream OK (0) job log log
2025/07/17 21:01 2h13m bisect fix upstream OK (0) job log log
2025/06/16 05:33 5h20m bisect fix upstream OK (0) job log log
2025/05/16 06:44 3h16m bisect fix upstream OK (0) job log log
2025/04/14 10:07 2h46m bisect fix upstream OK (0) job log log

Sample crash report:
------------[ cut here ]------------
==================================================================
BUG: KASAN: global-out-of-bounds in string_nocheck lib/vsprintf.c:632 [inline]
BUG: KASAN: global-out-of-bounds in string+0x229/0x2b0 lib/vsprintf.c:714
Read of size 1 at addr ffffffff8c74c10a by task syz-executor504/5826

CPU: 1 UID: 0 PID: 5826 Comm: syz-executor504 Not tainted 6.14.0-rc3-syzkaller-00079-g87a132e73910 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x16e/0x5b0 mm/kasan/report.c:521
 kasan_report+0x143/0x180 mm/kasan/report.c:634
 string_nocheck lib/vsprintf.c:632 [inline]
 string+0x229/0x2b0 lib/vsprintf.c:714
 vsnprintf+0x8b4/0x1220 lib/vsprintf.c:2843
 vprintk_store+0x482/0x1240 kernel/printk/printk.c:2279
 vprintk_emit+0x271/0xa10 kernel/printk/printk.c:2408
 __warn_printk+0x263/0x360 kernel/panic.c:797
 look_up_lock_class+0xdb/0x170 kernel/locking/lockdep.c:938
 register_lock_class+0x102/0x980 kernel/locking/lockdep.c:1292
 __lock_acquire+0xf3/0x2100 kernel/locking/lockdep.c:5103
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 __raw_spin_lock_irq include/linux/spinlock_api_smp.h:119 [inline]
 _raw_spin_lock_irq+0xd3/0x120 kernel/locking/spinlock.c:170
 spin_lock_irq include/linux/spinlock.h:376 [inline]
 rcu_pending_has_pending_or_armed fs/bcachefs/rcu_pending.c:592 [inline]
 rcu_pending_exit+0x13f/0x7a0 fs/bcachefs/rcu_pending.c:610
 bch2_fs_btree_key_cache_exit+0x8d1/0x9f0 fs/bcachefs/btree_key_cache.c:778
 __bch2_fs_free fs/bcachefs/super.c:569 [inline]
 bch2_fs_release+0x206/0x7b0 fs/bcachefs/super.c:624
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x231/0x480 lib/kobject.c:737
 deactivate_locked_super+0xc6/0x130 fs/super.c:473
 cleanup_mnt+0x41f/0x4b0 fs/namespace.c:1413
 task_work_run+0x251/0x310 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x13f/0x340 kernel/entry/common.c:218
 do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7e807c2577
Code: 07 00 48 83 c4 08 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 b8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffeee02cd28 EFLAGS: 00000206 ORIG_RAX: 00000000000000a6
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00007f7e807c2577
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffeee02cde0
RBP: 00007ffeee02cde0 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000206 R12: 00007ffeee02de50
R13: 000055557adeb6c0 R14: 431bde82d7b634db R15: 00007ffeee02de70
 </TASK>

The buggy address belongs to the variable:
 .str+0xa/0x20

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xc74c
flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002000 ffffea000031d308 ffffea000031d308 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffffffff8c74c000: 00 05 f9 f9 02 f9 f9 f9 06 f9 f9 f9 00 00 00 00
 ffffffff8c74c080: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff8c74c100: 00 01 f9 f9 00 00 00 04 f9 f9 f9 f9 00 00 00 00
                      ^
 ffffffff8c74c180: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff8c74c200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/20 18:21 upstream 87a132e73910 50668798 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-kasan-gce-root KASAN: global-out-of-bounds Read in rcu_pending_exit
2024/12/19 09:52 upstream eabcdba3ad40 1432fc84 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs KASAN: global-out-of-bounds Read in rcu_pending_exit
2025/01/06 19:48 linux-next 8155b4ef3466 f3558dbf .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root KASAN: global-out-of-bounds Read in rcu_pending_exit
2024/11/20 08:14 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7b1d1d4cfac0 7d02db5a .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 KASAN: global-out-of-bounds Read in rcu_pending_exit
2025/03/14 20:20 upstream 695caca9345a e2826670 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs BUG: unable to handle kernel paging request in rcu_pending_exit
* Struck through repros no longer work on HEAD.