linux-kernel - Re: [syzbot] [squashfs?] UBSAN: shift-out-of-bounds in squashfs_bio

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Message-ID: <67f1f6f6.050a0220.0a13.025a.GAE@google.com>
Date: Sat, 05 Apr 2025 20:37:26 -0700
From: syzbot <syzbot+65761fc25a137b9c8c6e@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org, phillip@...ashfs.org.uk, 
	squashfs-devel-owner@...ts.sourceforge.net, 
	squashfs-devel@...ts.sourceforge.net, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [squashfs?] UBSAN: shift-out-of-bounds in squashfs_bio_read

syzbot has found a reproducer for the following issue on:

HEAD commit:    56f944529ec2 Merge tag 'input-for-v6.15-rc0' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=167eab4c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f2054704dd53fb80
dashboard link: https://syzkaller.appspot.com/bug?extid=65761fc25a137b9c8c6e
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=1775dd98580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=113787e4580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-56f94452.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c6da83e5191b/vmlinux-56f94452.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5c060438ea13/bzImage-56f94452.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/f9d150e929ed/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+65761fc25a137b9c8c6e@...kaller.appspotmail.com

loop0: detected capacity change from 0 to 8
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36
shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long')
CPU: 0 UID: 0 PID: 5472 Comm: syz-executor224 Not tainted 6.14.0-syzkaller-13443-g56f944529ec2 #0 PREEMPT(full) 
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:492
 squashfs_bio_read+0xf7e/0x10b0 fs/squashfs/block.c:195
 squashfs_read_data+0x2e7/0xba0 fs/squashfs/block.c:333
 squashfs_read_table+0x338/0x390 fs/squashfs/cache.c:436
 squashfs_fill_super+0x238/0x21e0 fs/squashfs/super.c:216
 get_tree_bdev_flags+0x490/0x5c0 fs/super.c:1636
 vfs_get_tree+0x90/0x2b0 fs/super.c:1759
 do_new_mount+0x2cf/0xb70 fs/namespace.c:3879
 do_mount fs/namespace.c:4219 [inline]
 __do_sys_mount fs/namespace.c:4430 [inline]
 __se_sys_mount+0x38c/0x400 fs/namespace.c:4407
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbefca8001a
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:00007ffcb4b512c8 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffcb4b512e0 RCX: 00007fbefca8001a
RDX: 0000200000000240 RSI: 0000200000000280 RDI: 00007ffcb4b512e0
RBP: 0000200000000280 R08: 00007ffcb4b51320 R09: 0000000000000220
R10: 0000000000000000 R11: 0000000000000282 R12: 0000200000000240
R13: 00007ffcb4b51320 R14: 0000000000000003 R15: 0000000000000000
 </TASK>
---[ end trace ]---


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.