UBSAN: shift-out-of-bounds in validate_sb_layout

[Ubisectech Sirius]

Hello.
We are Ubisectech Sirius Team, the vulnerability lab of China ValiantSec. Recently, our team has discovered a issue in Linux kernel 6.7. Attached to the email were a PoC file of the issue.

Stack dump:
UBSAN: shift-out-of-bounds in fs/bcachefs/super-io.c:310:18
shift exponent 127 is too large for 32-bit type 'int'
CPU: 0 PID: 14408 Comm: syz-executor.3 Not tainted 6.7.0 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x136/0x150 lib/dump_stack.c:106
 ubsan_epilogue lib/ubsan.c:217 [inline]
 __ubsan_handle_shift_out_of_bounds+0x24b/0x430 lib/ubsan.c:387
 validate_sb_layout.cold+0x1a/0x51 fs/bcachefs/super-io.c:310
 bch2_read_super+0x980/0x1000 fs/bcachefs/super-io.c:786
 bch2_fs_open+0x471/0x3890 fs/bcachefs/super.c:1922
 bch2_mount+0x538/0x13c0 fs/bcachefs/fs.c:1863
 legacy_get_tree+0x109/0x220 fs/fs_context.c:662
 vfs_get_tree+0x93/0x380 fs/super.c:1771
 do_new_mount fs/namespace.c:3337 [inline]
 path_mount+0x679/0x1e40 fs/namespace.c:3664
 do_mount fs/namespace.c:3677 [inline]
 __do_sys_mount fs/namespace.c:3886 [inline]
 __se_sys_mount fs/namespace.c:3863 [inline]
 __x64_sys_mount+0x287/0x310 fs/namespace.c:3863
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x43/0x120 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f41e1091b3e
Code: 48 c7 c0 ff ff ff ff eb aa e8 be 0d 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 f3 0f 1e fa 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:00007f41e1d22e38 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000005d82 RCX: 00007f41e1091b3e
RDX: 0000000020005d80 RSI: 0000000020000100 RDI: 00007f41e1d22e90
RBP: 00007f41e1d22ed0 R08: 00007f41e1d22ed0 R09: 0000000000000080
R10: 0000000000000080 R11: 0000000000000202 R12: 0000000020005d80
R13: 0000000020000100 R14: 00007f41e1d22e90 R15: 0000000020005e00
 </TASK>

Thank you for taking the time to read this email and we look forward to working with you further.

Attachment: poc.c
Description: Binary data