Re: [syzbot] [bcachefs?] general protection fault in btree_node_iter_and_journal_peek

From: syzbot
Date: Tue Oct 22 2024 - 03:35:44 EST

syzbot has found a reproducer for 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=15d8c640580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fc6f8ce8c5369043
dashboard link: https://syzkaller.appspot.com/bug?extid=005ef9aa519f30d97657
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=117f9430580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13d8c640580000

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/c9f863564593/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+005ef9aa519f30d97657@xxxxxxxxxxxxxxxxxxxxxxxxx

bucket 0:41 data type btree ptr gen 0 missing in alloc btree
while marking u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 9aa2895aefce4bdf written 24 min_key POS_MIN durability: 1 ptr: 0:41:0 gen 0, fixing
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 5091 Comm: syz-executor910 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:bch2_bkey_buf_reassemble fs/bcachefs/bkey_buf.h:27 [inline]
RIP: 0010:btree_node_iter_and_journal_peek+0x260/0x1010 fs/bcachefs/btree_iter.c:886
Code: 4c 24 18 45 89 f0 50 53 41 51 e8 2b b3 00 00 48 83 c4 18 4c 89 ff e8 8f 87 00 00 48 89 c3 49 89 d7 48 c1 e8 03 48 89 44 24 18 <42> 0f b6 04 28 84 c0 4c 89 ea 0f 85 d1 0c 00 00 48 89 5c 24 38 44
RSP: 0018:ffffc9000b015fc0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 00000000000000ff RDI: ffffc9000b016174
RBP: ffffc9000b016250 R08: ffffc9000b016173 R09: 0000000000000000
R10: ffffc9000b016160 R11: fffff52001602c2f R12: ffffc9000b0161c0
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 000055558e598380(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c63dfb7508 CR3: 000000003f50c000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
btree_path_down fs/bcachefs/btree_iter.c:914 [inline]
bch2_btree_path_traverse_one+0x1981/0x2940 fs/bcachefs/btree_iter.c:1169
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_gc_btree fs/bcachefs/btree_gc.c:670 [inline]
bch2_gc_btrees fs/bcachefs/btree_gc.c:729 [inline]
bch2_check_allocations+0x1a8b/0x6e80 fs/bcachefs/btree_gc.c:1123
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: 0033:0x7f9107f3bbba
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:00007ffede58d8a8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffede58d8c0 RCX: 00007f9107f3bbba
RDX: 00000000200058c0 RSI: 0000000020005900 RDI: 00007ffede58d8c0
RBP: 0000000000000004 R08: 00007ffede58d900 R09: 00000000000058d0
R10: 0000000000010000 R11: 0000000000000282 R12: 0000000000010000
R13: 00007ffede58d900 R14: 0000000000000003 R15: 0000000001000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_bkey_buf_reassemble fs/bcachefs/bkey_buf.h:27 [inline]
RIP: 0010:btree_node_iter_and_journal_peek+0x260/0x1010 fs/bcachefs/btree_iter.c:886
Code: 4c 24 18 45 89 f0 50 53 41 51 e8 2b b3 00 00 48 83 c4 18 4c 89 ff e8 8f 87 00 00 48 89 c3 49 89 d7 48 c1 e8 03 48 89 44 24 18 <42> 0f b6 04 28 84 c0 4c 89 ea 0f 85 d1 0c 00 00 48 89 5c 24 38 44
RSP: 0018:ffffc9000b015fc0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 00000000000000ff RDI: ffffc9000b016174
RBP: ffffc9000b016250 R08: ffffc9000b016173 R09: 0000000000000000
R10: ffffc9000b016160 R11: fffff52001602c2f R12: ffffc9000b0161c0
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 000055558e598380(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005594e96c70c8 CR3: 000000003f50c000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 4c 24 18 rex.WR and $0x18,%al
3: 45 89 f0 mov %r14d,%r8d
6: 50 push %rax
7: 53 push %rbx
8: 41 51 push %r9
a: e8 2b b3 00 00 call 0xb33a
f: 48 83 c4 18 add $0x18,%rsp
13: 4c 89 ff mov %r15,%rdi
16: e8 8f 87 00 00 call 0x87aa
1b: 48 89 c3 mov %rax,%rbx
1e: 49 89 d7 mov %rdx,%r15
21: 48 c1 e8 03 shr $0x3,%rax
25: 48 89 44 24 18 mov %rax,0x18(%rsp)
* 2a: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 4c 89 ea mov %r13,%rdx
34: 0f 85 d1 0c 00 00 jne 0xd0b
3a: 48 89 5c 24 38 mov %rbx,0x38(%rsp)
3f: 44 rex.R


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