Re: [syzbot] [bcachefs?] UBSAN: array-index-out-of-bounds in bch2_bkey_swab_key

[Kent Overstreet]

On Sat, Jun 08, 2024 at 03:15:24PM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    d30d0e49da71 Merge tag 'net-6.10-rc3' of git://git.kernel...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=17cac096980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=9a6ac4277fffe3ea
> dashboard link: https://syzkaller.appspot.com/bug?extid=51837cbb6ca165f5344e
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/6d0ced9b3d02/disk-d30d0e49.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/cd5917307028/vmlinux-d30d0e49.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/cda11b4554fe/bzImage-d30d0e49.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+51837cbb6ca165f5344e@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> bcachefs (loop0): mounting version 1.7: mi_btree_bitmap opts=compression=lz4,nojournal_transaction_names
> bcachefs (loop0): recovering from clean shutdown, journal seq 7
> ------------[ cut here ]------------
> UBSAN: array-index-out-of-bounds in fs/bcachefs/bkey.c:1067:27
> index 5 is out of range for type '__u64[0]' (aka 'unsigned long long[0]')
> CPU: 0 PID: 5185 Comm: syz-executor.0 Not tainted 6.10.0-rc2-syzkaller-00222-gd30d0e49da71 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
>  ubsan_epilogue lib/ubsan.c:231 [inline]
>  __ubsan_handle_out_of_bounds+0x121/0x150 lib/ubsan.c:429
>  bch2_bkey_swab_key+0x224/0x240 fs/bcachefs/bkey.c:1067
>  __bch2_bkey_compat+0x2b3/0x1030 fs/bcachefs/bkey_methods.c:402
>  bch2_bkey_compat fs/bcachefs/bkey_methods.h:133 [inline]
>  validate_bset_keys+0x608/0x1a60 fs/bcachefs/btree_io.c:915
>  bch2_btree_node_read_done+0x250a/0x6750 fs/bcachefs/btree_io.c:1148
>  btree_node_read_work+0x68b/0x1260 fs/bcachefs/btree_io.c:1345
>  bch2_btree_node_read+0x2433/0x2a10
>  __bch2_btree_root_read fs/bcachefs/btree_io.c:1769 [inline]
>  bch2_btree_root_read+0x61e/0x970 fs/bcachefs/btree_io.c:1793
>  read_btree_roots+0x22d/0x7b0 fs/bcachefs/recovery.c:475
>  bch2_fs_recovery+0x2346/0x3720 fs/bcachefs/recovery.c:803
>  bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1031
>  bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2123
>  bch2_mount+0x6c0/0x1320 fs/bcachefs/fs.c:1917
>  legacy_get_tree+0xee/0x190 fs/fs_context.c:662
>  vfs_get_tree+0x90/0x2a0 fs/super.c:1780
>  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: 0033:0x7fe09a07e66a
> Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 09 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 b0 ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fe09adffef8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
> RAX: ffffffffffffffda RBX: 00007fe09adfff80 RCX: 00007fe09a07e66a
> RDX: 0000000020005d80 RSI: 0000000020005dc0 RDI: 00007fe09adfff40
> RBP: 0000000020005d80 R08: 00007fe09adfff80 R09: 0000000000000018
> R10: 0000000000000018 R11: 0000000000000202 R12: 0000000020005dc0
> R13: 00007fe09adfff40 R14: 0000000000005dab R15: 0000000020005e00
>  </TASK>
> ---[ end trace ]---
> 
> 
> ---
> 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 syzkaller@xxxxxxxxxxxxxxxx.
> 
> 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: bcachefs: Fix array-index-out-of-bounds