Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_alloc_to_text

syzbot
2024-10-22T01:50:04Z

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: shift-out-of-bounds in bch2_alloc_to_text

bcachefs (loop0): fatal error - emergency read only
bcachefs (loop0): insufficient writeable journal devices available: have 0, need 1
rw journal devs: loop0
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/bcachefs/alloc_background.h:165:13
shift exponent 129 is too large for 32-bit type 'unsigned int'
CPU: 0 UID: 0 PID: 5607 Comm: syz.0.15 Not tainted 6.12.0-rc3-syzkaller-00087-gc964ced77262-dirty #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
ubsan_epilogue lib/ubsan.c:231 [inline]
__ubsan_handle_shift_out_of_bounds+0x3c8/0x420 lib/ubsan.c:468
data_type_movable fs/bcachefs/alloc_background.h:165 [inline]
alloc_lru_idx_fragmentation fs/bcachefs/alloc_background.h:171 [inline]
bch2_alloc_to_text+0xc79/0xce0 fs/bcachefs/alloc_background.c:373
__bch2_bkey_fsck_err+0x1c8/0x280 fs/bcachefs/error.c:454
bch2_alloc_v4_validate+0x97b/0xf30 fs/bcachefs/alloc_background.c:259
bch2_btree_node_read_done+0x3e7e/0x5e90 fs/bcachefs/btree_io.c:1223
btree_node_read_work+0x68b/0x1260 fs/bcachefs/btree_io.c:1327
bch2_btree_node_read+0x2433/0x2a10
__bch2_btree_root_read fs/bcachefs/btree_io.c:1753 [inline]
bch2_btree_root_read+0x617/0x7a0 fs/bcachefs/btree_io.c:1775
read_btree_roots+0x296/0x840 fs/bcachefs/recovery.c:524
bch2_fs_recovery+0x2585/0x39c0 fs/bcachefs/recovery.c:854
bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1036
bch2_fs_get_tree+0xd68/0x1710 fs/bcachefs/fs.c:2174
vfs_get_tree+0x90/0x2b0 fs/super.c:1800
do_new_mount+0x2be/0xb40 fs/namespace.c:3507
do_mount fs/namespace.c:3847 [inline]
__do_sys_mount fs/namespace.c:4055 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4032
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: 0033:0x7fca2ff7f79a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 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:00007fca30df3e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fca30df3ef0 RCX: 00007fca2ff7f79a
RDX: 00000000200058c0 RSI: 0000000020000100 RDI: 00007fca30df3eb0
RBP: 00000000200058c0 R08: 00007fca30df3ef0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000100
R13: 00007fca30df3eb0 R14: 00000000000058cc R15: 0000000020005940
</TASK>
---[ end trace ]---

Tested on:

commit: c964ced7 Merge tag 'for-linus' of git://git.kernel.org..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=139890a7980000
kernel config: https://syzkaller.appspot.com/x/.config?x=cfbd94c114a3d407
dashboard link: https://syzkaller.appspot.com/bug?extid=7f45fa9805c40db3f108
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=15735c87980000