[syzbot] [bcachefs?] general protection fault in bch2_fs_btree_key_cache_exit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2ccbdf43d5e7 Merge tag 'for-linus' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=169faf7a980000
kernel config: https://syzkaller.appspot.com/x/.config?x=81c0d76ceef02b39
dashboard link: https://syzkaller.appspot.com/bug?extid=a7c01586b9012e998c07
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386

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-2ccbdf43.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/13cdb5bfbafa/vmlinux-2ccbdf43.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7a14f5d07f81/bzImage-2ccbdf43.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a7c015...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc000000001b: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000000d8-0x00000000000000df]
CPU: 1 PID: 5228 Comm: syz-executor.3 Not tainted 6.10.0-rc3-syzkaller-00044-g2ccbdf43d5e7 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:__list_add include/linux/list.h:154 [inline]
RIP: 0010:list_add include/linux/list.h:169 [inline]
RIP: 0010:bch2_fs_btree_key_cache_exit+0x90a/0x1490 fs/bcachefs/btree_key_cache.c:968
Code: 00 fc ff df 48 89 f8 48 c1 e8 03 80 3c 08 00 0f 85 7f 08 00 00 4c 89 e0 4d 89 66 08 48 b9 00 00 00 00 00 fc ff df 48 c1 e8 03 <80> 3c 08 00 0f 85 53 08 00 00 49 8d bf e0 00 00 00 4d 89 b7 d8 00
RSP: 0018:ffffc90002f6fc48 EFLAGS: 00010206
RAX: 000000000000001b RBX: 0000000000000000 RCX: dffffc0000000000
RDX: ffff88801d384880 RSI: ffffffff83ef4d76 RDI: ffff888012192a48
RBP: ffffe8ffad3699f8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000003 R12: 00000000000000d8
R13: ffffc90002f6fcc0 R14: ffff888012192a40 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88802c100000(0063) knlGS:0000000056f3a400
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000032229000 CR3: 000000004acf4000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__bch2_fs_free fs/bcachefs/super.c:554 [inline]
bch2_fs_release+0x107/0x870 fs/bcachefs/super.c:605
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:473
deactivate_super+0xde/0x100 fs/super.c:506
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+0x80/0x120 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: 0023:0xf72b7579
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:00000000ffd49be8 EFLAGS: 00000292 ORIG_RAX: 0000000000000034
RAX: 0000000000000000 RBX: 00000000ffd49c90 RCX: 0000000000000009
RDX: 00000000f740dff4 RSI: 00000000f735e361 RDI: 00000000ffd4ad34
RBP: 00000000ffd49c90 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:__list_add include/linux/list.h:154 [inline]
RIP: 0010:list_add include/linux/list.h:169 [inline]
RIP: 0010:bch2_fs_btree_key_cache_exit+0x90a/0x1490 fs/bcachefs/btree_key_cache.c:968
Code: 00 fc ff df 48 89 f8 48 c1 e8 03 80 3c 08 00 0f 85 7f 08 00 00 4c 89 e0 4d 89 66 08 48 b9 00 00 00 00 00 fc ff df 48 c1 e8 03 <80> 3c 08 00 0f 85 53 08 00 00 49 8d bf e0 00 00 00 4d 89 b7 d8 00
RSP: 0018:ffffc90002f6fc48 EFLAGS: 00010206
RAX: 000000000000001b RBX: 0000000000000000 RCX: dffffc0000000000
RDX: ffff88801d384880 RSI: ffffffff83ef4d76 RDI: ffff888012192a48
RBP: ffffe8ffad3699f8 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000003 R12: 00000000000000d8
R13: ffffc90002f6fcc0 R14: ffff888012192a40 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:0000000056f3a400
CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000c000b77000 CR3: 000000004acf4000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 3 bytes skipped:
0: df 48 89 fisttps -0x77(%rax)
3: f8 clc
4: 48 c1 e8 03 shr $0x3,%rax
8: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1)
c: 0f 85 7f 08 00 00 jne 0x891
12: 4c 89 e0 mov %r12,%rax
15: 4d 89 66 08 mov %r12,0x8(%r14)
19: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
20: fc ff df
23: 48 c1 e8 03 shr $0x3,%rax
* 27: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2b: 0f 85 53 08 00 00 jne 0x884
31: 49 8d bf e0 00 00 00 lea 0xe0(%r15),%rdi
38: 4d rex.WRB
39: 89 .byte 0x89
3a: b7 d8 mov $0xd8,%bh


---
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 syzk...@googlegroups.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 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

[Kent Overstreet]

#syz fix: bcachefs: Fix early error path in bch2_fs_btree_key_cache_exit()