[moderation] [bcachefs?] general protection fault in detach_if_pending (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ff2632d7d08e Merge tag 'powerpc-6.10-1' of git://git.kerne..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1723156c980000
kernel config: https://syzkaller.appspot.com/x/.config?x=11eee78d9c5171fd
dashboard link: https://syzkaller.appspot.com/bug?extid=3a0c08ac0475469ba2cc
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
CC: [bfo...@redhat.com kent.ov...@linux.dev linux-b...@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/7bc7510fe41f/non_bootable_disk-ff2632d7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/72bdffadf53c/vmlinux-ff2632d7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d2fd7e3c5081/bzImage-ff2632d7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3a0c08...@syzkaller.appspotmail.com

bcachefs (loop3): flushing journal and stopping allocators complete, journal seq 14
bcachefs (loop3): shutdown complete, journal seq 15
bcachefs (loop3): marking filesystem clean
bcachefs (loop3): shutdown complete
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 2 PID: 7155 Comm: syz-executor.3 Not tainted 6.9.0-syzkaller-08410-gff2632d7d08e #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__hlist_del include/linux/list.h:988 [inline]
RIP: 0010:detach_timer kernel/time/timer.c:935 [inline]
RIP: 0010:detach_if_pending+0x14c/0x450 kernel/time/timer.c:954
Code: df 4c 89 ea 4c 8b 23 48 c1 ea 03 80 3c 02 00 0f 85 ea 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 6b 08 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 be 02 00 00 4d 85 e4 4d 89 65 00 74 2a e8 3c 5b
RSP: 0018:ffffc900041bfba0 EFLAGS: 00010003
RAX: dffffc0000000000 RBX: ffffe8ffad250ed0 RCX: ffffffff817b2afa
RDX: 0000000000000007 RSI: ffffffff817b291e RDI: 0000000000000001
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 000000000000003d R14: 0000000000000001 R15: 000000000003d78c
FS: 0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:0000000057178400
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000c000820000 CR3: 000000005a272000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__try_to_del_timer_sync+0xc5/0x170 kernel/time/timer.c:1510
__timer_delete_sync+0xf4/0x1b0 kernel/time/timer.c:1666
del_timer_sync include/linux/timer.h:185 [inline]
cleanup_srcu_struct+0x124/0x520 kernel/rcu/srcutree.c:659
bch2_fs_btree_iter_exit+0x46e/0x630 fs/bcachefs/btree_iter.c:3279
__bch2_fs_free fs/bcachefs/super.c:562 [inline]
bch2_fs_release+0xfb/0x670 fs/bcachefs/super.c:610
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x1fa/0x5b0 lib/kobject.c:737
deactivate_locked_super+0xbe/0x1a0 fs/super.c:472
deactivate_super+0xde/0x100 fs/super.c:505
cleanup_mnt+0x222/0x450 fs/namespace.c:1267
task_work_run+0x14e/0x250 kernel/task_work.c:180
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:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x278/0x2a0 kernel/entry/common.c:218
__do_fast_syscall_32+0x82/0x120 arch/x86/entry/common.c:389
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7304579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000ffd40488 EFLAGS: 00000292 ORIG_RAX: 0000000000000034
RAX: 0000000000000000 RBX: 00000000ffd40530 RCX: 0000000000000009
RDX: 00000000f745aff4 RSI: 00000000f73ab361 RDI: 00000000ffd415d4
RBP: 00000000ffd40530 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__hlist_del include/linux/list.h:988 [inline]
RIP: 0010:detach_timer kernel/time/timer.c:935 [inline]
RIP: 0010:detach_if_pending+0x14c/0x450 kernel/time/timer.c:954
Code: df 4c 89 ea 4c 8b 23 48 c1 ea 03 80 3c 02 00 0f 85 ea 02 00 00 48 b8 00 00 00 00 00 fc ff df 4c 8b 6b 08 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 be 02 00 00 4d 85 e4 4d 89 65 00 74 2a e8 3c 5b
RSP: 0018:ffffc900041bfba0 EFLAGS: 00010003
RAX: dffffc0000000000 RBX: ffffe8ffad250ed0 RCX: ffffffff817b2afa
RDX: 0000000000000007 RSI: ffffffff817b291e RDI: 0000000000000001
RBP: 0000000000000001 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: 000000000000003d R14: 0000000000000001 R15: 000000000003d78c
FS: 0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:0000000057178400
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000c000820000 CR3: 000000005a272000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: df 4c 89 ea fisttps -0x16(%rcx,%rcx,4)
4: 4c 8b 23 mov (%rbx),%r12
7: 48 c1 ea 03 shr $0x3,%rdx
b: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
f: 0f 85 ea 02 00 00 jne 0x2ff
15: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1c: fc ff df
1f: 4c 8b 6b 08 mov 0x8(%rbx),%r13
23: 4c 89 ea mov %r13,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 be 02 00 00 jne 0x2f2
34: 4d 85 e4 test %r12,%r12
37: 4d 89 65 00 mov %r12,0x0(%r13)
3b: 74 2a je 0x67
3d: e8 .byte 0xe8
3e: 3c 5b cmp $0x5b,%al


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