[syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_btree_lost_data

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8c06da67d0bd Merge tag 'livepatching-for-6.10' of git://gi..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=135f87d4980000
kernel config: https://syzkaller.appspot.com/x/.config?x=cc69cd6a2dcb5aa
dashboard link: https://syzkaller.appspot.com/bug?extid=29f65db1a5fe427b5c56
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=12d09ce0980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10ea775c980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/331202aeac12/disk-8c06da67.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4db56871f364/vmlinux-8c06da67.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2ab7bc870390/bzImage-8c06da67.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b709a5f7f34f/mount_0.gz

The issue was bisected to:

commit 55936afe11077a84d9e1c5068169af328bbf2811
Author: Kent Overstreet <kent.ov...@linux.dev>
Date: Sat Mar 16 03:03:42 2024 +0000

bcachefs: Flag btrees with missing data

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=145dc1d0980000
final oops: https://syzkaller.appspot.com/x/report.txt?x=165dc1d0980000
console output: https://syzkaller.appspot.com/x/log.txt?x=125dc1d0980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+29f65d...@syzkaller.appspotmail.com
Fixes: 55936afe1107 ("bcachefs: Flag btrees with missing data")

bcachefs (loop0): mounting version 1.7: mi_btree_bitmap opts=metadata_checksum=none,data_checksum=none,nojournal_transaction_names
bcachefs (loop0): recovering from clean shutdown, journal seq 10
bcachefs (loop0): error validating btree node on loop0 at btree (unknown) level 3/3
u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 27c2ec7b8e70cb08 written 16 min_key POS_MIN durability: 1 ptr: 0:31:0 gen 0
node offset 0/16 bset u64s 0: incorrect btree id
bcachefs (loop0): inconsistency detected - emergency read only at journal seq 10
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/bcachefs/recovery.c:38:10
shift exponent 255 is too large for 64-bit type 'unsigned long long'
CPU: 1 PID: 5082 Comm: syz-executor184 Not tainted 6.9.0-syzkaller-07387-g8c06da67d0bd #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_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468
bch2_btree_lost_data+0x143/0x150 fs/bcachefs/recovery.c:38
bch2_btree_node_read_done+0x50f9/0x5a40 fs/bcachefs/btree_io.c:1272
btree_node_read_work+0x665/0x1300 fs/bcachefs/btree_io.c:1324
bch2_btree_node_read+0x2b64/0x32c0
__bch2_btree_root_read fs/bcachefs/btree_io.c:1748 [inline]
bch2_btree_root_read+0x61e/0x970 fs/bcachefs/btree_io.c:1772
read_btree_roots+0x22d/0x7b0 fs/bcachefs/recovery.c:457
bch2_fs_recovery+0x4334/0x63b0 fs/bcachefs/recovery.c:785
bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1043
bch2_fs_open+0xa8d/0xdf0 fs/bcachefs/super.c:2105
bch2_mount+0x71d/0x1320 fs/bcachefs/fs.c:1906
legacy_get_tree+0xee/0x190 fs/fs_context.c:662
vfs_get_tree+0x90/0x2a0 fs/super.c:1779
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+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa695417daa
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:00007ffc4c8ca6b8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc4c8ca6d0 RCX: 00007fa695417daa
RDX: 0000000020011a00 RSI: 0000000020000080 RDI: 00007ffc4c8ca6d0
RBP: 0000000000000004 R08: 00007ffc4c8ca710 R09: 00000000000119fd
R10: 0000000001200014 R11: 0000000000000282 R12: 0000000001200014
R13: 00007ffc4c8ca710 R14: 0000000000000003 R15: 0000000001000000
</TASK>
---[ end trace ]---


---
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