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

Status: upstream: reported syz repro on 2024/11/25 14:18
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+e733ab672a1b6724c27f@syzkaller.appspotmail.com
First crash: 60d, last: 13d
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
  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] KASAN: global-out-of-bounds Read in rcu_pending_exit 0 (3) 2025/01/09 15:40
▶ ▼ Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/01/04 03:04 16m retest repro upstream report log

Sample crash report:
------------[ cut here ]------------
==================================================================
BUG: KASAN: global-out-of-bounds in string_nocheck lib/vsprintf.c:646 [inline]
BUG: KASAN: global-out-of-bounds in string+0x218/0x2b0 lib/vsprintf.c:728
Read of size 1 at addr ffffffff8c53984a by task syz.0.174/7554

CPU: 1 UID: 0 PID: 7554 Comm: syz.0.174 Not tainted 6.13.0-rc3-syzkaller-00073-geabcdba3ad40 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024
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:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 string_nocheck lib/vsprintf.c:646 [inline]
 string+0x218/0x2b0 lib/vsprintf.c:728
 vsnprintf+0x1101/0x1da0 lib/vsprintf.c:2848
 vprintk_store+0x485/0x1240 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:936
 register_lock_class+0x102/0x980 kernel/locking/lockdep.c:1290
 __lock_acquire+0xf3/0x2100 kernel/locking/lockdep.c:5101
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
 __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:576 [inline]
 rcu_pending_exit+0x13f/0x7a0 fs/bcachefs/rcu_pending.c:594
 bch2_fs_btree_key_cache_exit+0x97f/0xab0 fs/bcachefs/btree_key_cache.c:741
 __bch2_fs_free fs/bcachefs/super.c:556 [inline]
 bch2_fs_release+0x206/0x7d0 fs/bcachefs/super.c:611
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x22f/0x480 lib/kobject.c:737
 bch2_fs_alloc fs/bcachefs/super.c:960 [inline]
 bch2_fs_open+0x1ebe/0x2f80 fs/bcachefs/super.c:2065
 bch2_fs_get_tree+0x738/0x1710 fs/bcachefs/fs.c:2157
 vfs_get_tree+0x90/0x2b0 fs/super.c:1814
 do_new_mount+0x2be/0xb40 fs/namespace.c:3507
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4057 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4034
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb98f7874ca
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007fb99051be68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fb99051bef0 RCX: 00007fb98f7874ca
RDX: 00000000200000c0 RSI: 0000000020000000 RDI: 00007fb99051beb0
RBP: 00000000200000c0 R08: 00007fb99051bef0 R09: 0000000000800000
R10: 0000000000800000 R11: 0000000000000246 R12: 0000000020000000
R13: 00007fb99051beb0 R14: 0000000000005938 R15: 0000000020005b00
 </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:0xc539
flags: 0xfff00000002000(reserved|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000002000 ffffea0000314e48 ffffea0000314e48 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:
 ffffffff8c539700: 02 f9 f9 f9 00 00 06 f9 f9 f9 f9 f9 00 00 03 f9
 ffffffff8c539780: f9 f9 f9 f9 00 00 00 00 f9 f9 f9 f9 00 00 00 00
>ffffffff8c539800: 00 00 00 00 00 00 00 00 00 01 f9 f9 00 00 00 04
                                              ^
 ffffffff8c539880: f9 f9 f9 f9 00 00 00 00 00 00 00 00 00 00 00 00
 ffffffff8c539900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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
* Struck through repros no longer work on HEAD.