[syzbot] [bcachefs?] general protection fault in bch2_checksum

syzbot
2024-07-17T13:39:20Z

Hello,

syzbot found the following issue on:

HEAD commit: 0434dbe32053 Merge tag 'linux_kselftest-next-6.11-rc1' of ..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16061f4e980000
kernel config: https://syzkaller.appspot.com/x/.config?x=4b8bd5292e033239
dashboard link: https://syzkaller.appspot.com/bug?extid=dd3d9835055dacb66f35
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=10d9ccb5980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12633a79980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3766752b5090/disk-0434dbe3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e3608abc3f91/vmlinux-0434dbe3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c133560ad498/bzImage-0434dbe3.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/ff0cf9ecbd00/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+dd3d9835055dacb66f35@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 32768
Oops: general protection fault, probably for non-canonical address 0xdffffc000000900d: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: probably user-memory-access in range [0x0000000000048068-0x000000000004806f]
CPU: 0 PID: 5080 Comm: syz-executor457 Not tainted 6.10.0-syzkaller-02711-g0434dbe32053 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
RIP: 0010:gen_poly_key fs/bcachefs/checksum.c:191 [inline]
RIP: 0010:bch2_checksum+0x1c5/0x770 fs/bcachefs/checksum.c:227
Code: f6 e8 3f c5 dc fd 48 8b 44 24 28 4c 8d b0 68 80 04 00 ba 20 00 00 00 48 8d 7c 24 60 31 f6 e8 22 c5 dc fd 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 3c c2 dc fd 49 8b 3e 48 b8 00 00
RSP: 0018:ffffc90003536d40 EFLAGS: 00010202
RAX: 000000000000900d RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc90003536dc0
RBP: ffffc900035370b0 R08: ffffc90003536dbf R09: 0000000000000000
R10: ffffc90003536da0 R11: fffff520006a6db8 R12: ffffc90003536de0
R13: dffffc0000000000 R14: 0000000000048068 R15: 1ffff920006a6db0
FS: 000055558465b380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005568164b48e0 CR3: 0000000020ce4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
read_one_super+0xd87/0xf40 fs/bcachefs/super-io.c:673
__bch2_read_super+0x873/0x1370 fs/bcachefs/super-io.c:751
bch2_fs_open+0x246/0xdf0 fs/bcachefs/super.c:2082
bch2_mount+0x6b0/0x13c0 fs/bcachefs/fs.c:1931
legacy_get_tree+0xee/0x190 fs/fs_context.c:662
vfs_get_tree+0x90/0x2a0 fs/super.c:1789
do_new_mount+0x2be/0xb40 fs/namespace.c:3472
do_mount fs/namespace.c:3812 [inline]
__do_sys_mount fs/namespace.c:4020 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3997
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: 0033:0x7feb9e3d106a
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:00007ffd63a40f78 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffd63a40f90 RCX: 00007feb9e3d106a
RDX: 0000000020005b00 RSI: 0000000020000040 RDI: 00007ffd63a40f90
RBP: 0000000000000004 R08: 00007ffd63a40fd0 R09: 0000000000005b4e
R10: 0000000000000000 R11: 0000000000000282 R12: 0000000000000000
R13: 00007ffd63a40fd0 R14: 0000000000000003 R15: 0000000001000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:gen_poly_key fs/bcachefs/checksum.c:191 [inline]
RIP: 0010:bch2_checksum+0x1c5/0x770 fs/bcachefs/checksum.c:227
Code: f6 e8 3f c5 dc fd 48 8b 44 24 28 4c 8d b0 68 80 04 00 ba 20 00 00 00 48 8d 7c 24 60 31 f6 e8 22 c5 dc fd 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 3c c2 dc fd 49 8b 3e 48 b8 00 00
RSP: 0018:ffffc90003536d40 EFLAGS: 00010202
RAX: 000000000000900d RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc90003536dc0
RBP: ffffc900035370b0 R08: ffffc90003536dbf R09: 0000000000000000
R10: ffffc90003536da0 R11: fffff520006a6db8 R12: ffffc90003536de0
R13: dffffc0000000000 R14: 0000000000048068 R15: 1ffff920006a6db0
FS: 000055558465b380(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005568163d0fb0 CR3: 0000000020ce4000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: e8 3f c5 dc fd call 0xfddcc544
5: 48 8b 44 24 28 mov 0x28(%rsp),%rax
a: 4c 8d b0 68 80 04 00 lea 0x48068(%rax),%r14
11: ba 20 00 00 00 mov $0x20,%edx
16: 48 8d 7c 24 60 lea 0x60(%rsp),%rdi
1b: 31 f6 xor %esi,%esi
1d: e8 22 c5 dc fd call 0xfddcc544
22: 4c 89 f0 mov %r14,%rax
25: 48 c1 e8 03 shr $0x3,%rax
* 29: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 f7 mov %r14,%rdi
33: e8 3c c2 dc fd call 0xfddcc274
38: 49 8b 3e mov (%r14),%rdi
3b: 48 rex.W
3c: b8 .byte 0xb8

---
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