[syzbot] [bcachefs?] general protection fault in bch2_btree_path_traverse_one

syzbot
2024-10-25T06:48:30Z

Hello,

syzbot found the following issue on:

HEAD commit: c2ee9f594da8 KVM: selftests: Fix build on on non-x86 archi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=126cd0a7980000
kernel config: https://syzkaller.appspot.com/x/.config?x=fc6f8ce8c5369043
dashboard link: https://syzkaller.appspot.com/bug?extid=e22007d6acb9c87c2362
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=166cd0a7980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15378287980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-c2ee9f59.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8a3541902b13/vmlinux-c2ee9f59.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a00efacc2604/bzImage-c2ee9f59.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/1b5cb4a585a3/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e22007d6acb9c87c2362@syzkaller.appspotmail.com

bcachefs (loop0): stripes_read... done
bcachefs (loop0): snapshots_read... done
bcachefs (loop0): check_allocations... done
bcachefs (loop0): going read-write
bcachefs (loop0): journal_replay...
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000013: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000098-0x000000000000009f]
CPU: 0 UID: 0 PID: 5090 Comm: syz-executor250 Not tainted 6.12.0-rc4-syzkaller-00047-gc2ee9f594da8 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:btree_path_lock_root fs/bcachefs/btree_iter.c:732 [inline]
RIP: 0010:bch2_btree_path_traverse_one+0x94a/0x2940 fs/bcachefs/btree_iter.c:1170
Code: 89 44 24 60 42 80 3c 20 00 74 08 4c 89 ef e8 cd ea e5 fd 49 8b 45 00 48 89 44 24 48 48 8d 90 98 00 00 00 48 89 d0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 48 89 94 24 80 00 00 00 0f 85 ee 10 00 00 4c
RSP: 0018:ffffc9000aebcf40 EFLAGS: 00010202
RAX: 0000000000000013 RBX: 0000000000000000 RCX: ffff8880008da440
RDX: 0000000000000098 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000aebd230 R08: ffffffff8418b260 R09: ffffffff841892d9
R10: 0000000000000002 R11: ffff8880008da440 R12: dffffc0000000000
R13: ffff888041d014d8 R14: ffff888040254408 R15: 000000000000110b
FS: 0000555564217380(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005564fb1350d0 CR3: 0000000040b92000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
bch2_btree_path_traverse fs/bcachefs/btree_iter.h:247 [inline]
__bch2_btree_iter_peek fs/bcachefs/btree_iter.c:2197 [inline]
bch2_btree_iter_peek_upto+0xb58/0x70e0 fs/bcachefs/btree_iter.c:2297
bch2_btree_iter_peek_upto_type fs/bcachefs/btree_iter.h:685 [inline]
bch2_bucket_alloc_freelist fs/bcachefs/alloc_foreground.c:491 [inline]
bch2_bucket_alloc_trans+0x1122/0x3a50 fs/bcachefs/alloc_foreground.c:644
bch2_bucket_alloc_set_trans+0x517/0xd30 fs/bcachefs/alloc_foreground.c:804
__open_bucket_add_buckets+0x10dc/0x1b60 fs/bcachefs/alloc_foreground.c:1049
open_bucket_add_buckets+0x33a/0x410 fs/bcachefs/alloc_foreground.c:1093
bch2_alloc_sectors_start_trans+0xce9/0x2030
__bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:343 [inline]
bch2_btree_reserve_get+0x612/0x1890 fs/bcachefs/btree_update_interior.c:554
bch2_btree_update_start+0xe56/0x14e0 fs/bcachefs/btree_update_interior.c:1252
bch2_btree_split_leaf+0x123/0x840 fs/bcachefs/btree_update_interior.c:1850
bch2_trans_commit_error+0x212/0x1390 fs/bcachefs/btree_trans_commit.c:942
__bch2_trans_commit+0x7ead/0x93c0 fs/bcachefs/btree_trans_commit.c:1140
bch2_trans_commit fs/bcachefs/btree_update.h:184 [inline]
bch2_journal_replay+0x1a3a/0x2a40 fs/bcachefs/recovery.c:318
bch2_run_recovery_pass+0xf0/0x1e0 fs/bcachefs/recovery_passes.c:185
bch2_run_recovery_passes+0x387/0x870 fs/bcachefs/recovery_passes.c:232
bch2_fs_recovery+0x25cc/0x39c0 fs/bcachefs/recovery.c:862
bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1036
bch2_fs_get_tree+0xd68/0x1710 fs/bcachefs/fs.c:2174
vfs_get_tree+0x90/0x2b0 fs/super.c:1800
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: 0033:0x7f4a8f435cba
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc0b30fb48 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc0b30fb60 RCX: 00007f4a8f435cba
RDX: 00000000200058c0 RSI: 0000000020005900 RDI: 00007ffc0b30fb60
RBP: 0000000000000004 R08: 00007ffc0b30fba0 R09: 00000000000058dd
R10: 0000000000010000 R11: 0000000000000282 R12: 0000000000010000
R13: 00007ffc0b30fba0 R14: 0000000000000003 R15: 0000000001000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:btree_path_lock_root fs/bcachefs/btree_iter.c:732 [inline]
RIP: 0010:bch2_btree_path_traverse_one+0x94a/0x2940 fs/bcachefs/btree_iter.c:1170
Code: 89 44 24 60 42 80 3c 20 00 74 08 4c 89 ef e8 cd ea e5 fd 49 8b 45 00 48 89 44 24 48 48 8d 90 98 00 00 00 48 89 d0 48 c1 e8 03 <42> 0f b6 04 20 84 c0 48 89 94 24 80 00 00 00 0f 85 ee 10 00 00 4c
RSP: 0018:ffffc9000aebcf40 EFLAGS: 00010202
RAX: 0000000000000013 RBX: 0000000000000000 RCX: ffff8880008da440
RDX: 0000000000000098 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc9000aebd230 R08: ffffffff8418b260 R09: ffffffff841892d9
R10: 0000000000000002 R11: ffff8880008da440 R12: dffffc0000000000
R13: ffff888041d014d8 R14: ffff888040254408 R15: 000000000000110b
FS: 0000555564217380(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005564fb1350d0 CR3: 0000000040b92000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 89 44 24 60 mov %eax,0x60(%rsp)
4: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
9: 74 08 je 0x13
b: 4c 89 ef mov %r13,%rdi
e: e8 cd ea e5 fd call 0xfde5eae0
13: 49 8b 45 00 mov 0x0(%r13),%rax
17: 48 89 44 24 48 mov %rax,0x48(%rsp)
1c: 48 8d 90 98 00 00 00 lea 0x98(%rax),%rdx
23: 48 89 d0 mov %rdx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 0f b6 04 20 movzbl (%rax,%r12,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 48 89 94 24 80 00 00 mov %rdx,0x80(%rsp)
38: 00
39: 0f 85 ee 10 00 00 jne 0x112d
3f: 4c rex.WR

---
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