[syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_blacklist_entries_gc

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 563a50672d8a Merge tag 'xfs-6.10-fixes-4' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1286cdda980000
kernel config: https://syzkaller.appspot.com/x/.config?x=c3820d4fff43c7a3
dashboard link: https://syzkaller.appspot.com/bug?extid=835d255ad6bc7f29ee12
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15e2d08e980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1009808e980000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-563a5067.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6ef95d163dde/vmlinux-563a5067.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0102d9e1ac9a/bzImage-563a5067.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/7fdc5cd163b4/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+835d25...@syzkaller.appspotmail.com

bcachefs (loop0): stripes_read... done
bcachefs (loop0): snapshots_read... done
bcachefs (loop0): journal_replay... done
bcachefs (loop0): resume_logged_ops... done
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in ./include/linux/log2.h:67:13
shift exponent 4294967295 is too large for 64-bit type 'long unsigned int'
CPU: 0 PID: 5189 Comm: syz-executor355 Not tainted 6.10.0-rc4-syzkaller-00283-g563a50672d8a #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:114
ubsan_epilogue lib/ubsan.c:231 [inline]
__ubsan_handle_shift_out_of_bounds+0x2a5/0x480 lib/ubsan.c:468
__rounddown_pow_of_two include/linux/log2.h:67 [inline]
eytzinger1_first fs/bcachefs/eytzinger.h:51 [inline]
eytzinger0_first fs/bcachefs/eytzinger.h:194 [inline]
bch2_blacklist_entries_gc.cold+0x35/0x56 fs/bcachefs/journal_seq_blacklist.c:235
bch2_fs_recovery+0x3240/0x3e40 fs/bcachefs/recovery.c:897
bch2_fs_start+0x2e9/0x600 fs/bcachefs/super.c:1036
bch2_fs_open+0xfa0/0x1110 fs/bcachefs/super.c:2128
bch2_mount+0xe2c/0x1230 fs/bcachefs/fs.c:1926
legacy_get_tree+0x109/0x220 fs/fs_context.c:662
vfs_get_tree+0x8f/0x380 fs/super.c:1780
do_new_mount fs/namespace.c:3352 [inline]
path_mount+0x14e6/0x1f20 fs/namespace.c:3679
do_mount fs/namespace.c:3692 [inline]
__do_sys_mount fs/namespace.c:3898 [inline]
__se_sys_mount fs/namespace.c:3875 [inline]
__x64_sys_mount+0x297/0x320 fs/namespace.c:3875
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd8395e2bba
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:00007ffe022b6078 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffe022b6090 RCX: 00007fd8395e2bba
RDX: 0000000020011a00 RSI: 0000000020000040 RDI: 00007ffe022b6090
RBP: 0000000000000004 R08: 00007ffe022b60d0 R09: 00000000000119f4
R10: 0000000001200014 R11: 0000000000000282 R12: 0000000001200014
R13: 00007ffe022b60d0 R14: 0000000000000003 R15: 0000000001000000
</TASK>
---[ end trace ]---


---
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***

Subject: UBSAN: shift-out-of-bounds in bch2_blacklist_entries_gc
Author: peil...@gmail.com

#syz test

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+835d25...@syzkaller.appspotmail.com

Tested on:

commit: 55027e68 Merge tag 'input-for-v6.10-rc5' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1191153e980000
kernel config: https://syzkaller.appspot.com/x/.config?x=d6b9ee98d841760c

dashboard link: https://syzkaller.appspot.com/bug?extid=835d255ad6bc7f29ee12
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=15ca4301980000

Note: testing is done by a robot and is best-effort only.