[syzbot] [bcachefs?] general protection fault in bch2_opts_apply

From: syzbot
Date: Mon Jul 15 2024 - 23:25:32 EST

Hello,

syzbot found the following issue on:

HEAD commit: 5e0497553643 Merge branch 'link_path_walk'
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11d2e3e1980000
kernel config: https://syzkaller.appspot.com/x/.config?x=283288d3d08ee56f
dashboard link: https://syzkaller.appspot.com/bug?extid=c55b814203b2ecab10bb
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=14bd24b5980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/261c3e7d5786/disk-5e049755.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c8c2016ade71/vmlinux-5e049755.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a12469ba78b6/bzImage-5e049755.xz
mounted in repro #1: https://storage.googleapis.com/syzbot-assets/63c33ff217d1/mount_0.gz
mounted in repro #2: https://storage.googleapis.com/syzbot-assets/6fd311b2dd60/mount_1.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c55b814203b2ecab10bb@xxxxxxxxxxxxxxxxxxxxxxxxx

Oops: general protection fault, probably for non-canonical address 0xdffffc00000000ea: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000750-0x0000000000000757]
CPU: 0 PID: 5957 Comm: syz.0.90 Not tainted 6.10.0-syzkaller-00017-g5e0497553643 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
RIP: 0010:bch2_opts_apply+0x175/0x4710 fs/bcachefs/opts.c:179
Code: c0 0f 85 88 28 00 00 44 89 3b 48 8d 5c 24 40 41 f6 c6 04 0f 84 5d 19 00 00 e8 b7 23 5d fd 4d 8d 7c 24 08 4c 89 e0 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 75 28 00 00 4c 89 f8 48 c1 e8 03 42 0f
RSP: 0018:ffffc900032d7820 EFLAGS: 00010212
RAX: 00000000000000ea RBX: ffffc900032d7860 RCX: ffff88802046da00
RDX: 0000000000000000 RSI: ffffc900032d7a40 RDI: ffffc900032d7900
RBP: ffffc900032d7990 R08: ffffffff8427ea52 R09: 1ffffffff1f5b2ad
R10: dffffc0000000000 R11: fffffbfff1f5b2ae R12: 0000000000000751
R13: dffffc0000000000 R14: 0080000000000004 R15: 0000000000000759
FS: 000055557be6c500(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0c3ffff000 CR3: 000000002bf8e000 CR4: 0000000000350ef0
Call Trace:
<TASK>
bch2_mount+0x774/0x13c0 fs/bcachefs/fs.c:1946
legacy_get_tree+0xf0/0x190 fs/fs_context.c:662
vfs_get_tree+0x92/0x2a0 fs/super.c:1789
do_new_mount+0x2be/0xb40 fs/namespace.c:3352
do_mount fs/namespace.c:3692 [inline]
__do_sys_mount fs/namespace.c:3898 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
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: 0033:0x7f1cb79772da
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 7e 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:00007fff0b6bb668 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fff0b6bb6f0 RCX: 00007f1cb79772da
RDX: 0000000020000000 RSI: 0000000020000040 RDI: 00007fff0b6bb6b0
RBP: 0000000020000000 R08: 00007fff0b6bb6f0 R09: 0000000000000010
R10: 0000000000000010 R11: 0000000000000246 R12: 0000000020000040
R13: 00007fff0b6bb6b0 R14: 0000000000005ba5 R15: 00000000200000c0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_opts_apply+0x175/0x4710 fs/bcachefs/opts.c:179
Code: c0 0f 85 88 28 00 00 44 89 3b 48 8d 5c 24 40 41 f6 c6 04 0f 84 5d 19 00 00 e8 b7 23 5d fd 4d 8d 7c 24 08 4c 89 e0 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 75 28 00 00 4c 89 f8 48 c1 e8 03 42 0f
RSP: 0018:ffffc900032d7820 EFLAGS: 00010212
RAX: 00000000000000ea RBX: ffffc900032d7860 RCX: ffff88802046da00
RDX: 0000000000000000 RSI: ffffc900032d7a40 RDI: ffffc900032d7900
RBP: ffffc900032d7990 R08: ffffffff8427ea52 R09: 1ffffffff1f5b2ad
R10: dffffc0000000000 R11: fffffbfff1f5b2ae R12: 0000000000000751
R13: dffffc0000000000 R14: 0080000000000004 R15: 0000000000000759
FS: 000055557be6c500(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff710d25000 CR3: 000000002bf8e000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
0: c0 0f 85 rorb $0x85,(%rdi)
3: 88 28 mov %ch,(%rax)
5: 00 00 add %al,(%rax)
7: 44 89 3b mov %r15d,(%rbx)
a: 48 8d 5c 24 40 lea 0x40(%rsp),%rbx
f: 41 f6 c6 04 test $0x4,%r14b
13: 0f 84 5d 19 00 00 je 0x1976
19: e8 b7 23 5d fd call 0xfd5d23d5
1e: 4d 8d 7c 24 08 lea 0x8(%r12),%r15
23: 4c 89 e0 mov %r12,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 0f 85 75 28 00 00 jne 0x28ac
37: 4c 89 f8 mov %r15,%rax
3a: 48 c1 e8 03 shr $0x3,%rax
3e: 42 rex.X
3f: 0f .byte 0xf


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