UBSAN: shift-out-of-bounds in squashfs_bio

UBSAN: shift-out-of-bounds in squashfs_bio_read

Status: upstream: reported C repro on 2025/04/05 07:36
Subsystems: squashfs
[Documentation on labels]
Reported-by: syzbot+65761fc25a137b9c8c6e@syzkaller.appspotmail.com
Fix commit: Squashfs: check return result of sb_min_blocksize
Patched on: [ci-upstream-linux-next-kasan-gce-root], missing on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb]
First crash: 59d, last: 1d15h

▶ ▼ Discussions (2)

Title	Replies (including bot)	Last reply
[PATCH] Squashfs: check return result of sb_min_blocksize	1 (1)	2025/04/09 02:47
[syzbot] [squashfs?] UBSAN: shift-out-of-bounds in squashfs_bio_read	2 (4)	2025/04/08 04:18

Sample crash report:

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 ]---

Crashes (8):
Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Assets (help?)	Manager	Title
2025/04/06 03:37	upstream	56f944529ec2	1c65791e	.config	console log	report	syz / log	C		[disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro]	ci-snapshot-upstream-root	UBSAN: shift-out-of-bounds in squashfs_bio_read
2025/04/01 07:29	upstream	609706855d90	36d76a97	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-kasan-gce-root	UBSAN: shift-out-of-bounds in squashfs_bio_read
2025/05/29 04:25	upstream	feacb1774bd5	3d2f584d	.config	console log	report				[disk image (non-bootable)] [vmlinux] [kernel image]	ci-snapshot-upstream-root	UBSAN: shift-out-of-bounds in squashfs_bio_read
2025/05/27 02:45	upstream	ddddf9d64f73	874a1386	.config	console log	report				[disk image (non-bootable)] [vmlinux] [kernel image]	ci-snapshot-upstream-root	UBSAN: shift-out-of-bounds in squashfs_bio_read
2025/05/22 14:51	upstream	d608703fcdd9	0919b50b	.config	console log	report				[disk image (non-bootable)] [vmlinux] [kernel image]	ci-snapshot-upstream-root	UBSAN: shift-out-of-bounds in squashfs_bio_read
2025/05/17 15:49	upstream	172a9d94339c	f41472b0	.config	console log	report				[disk image (non-bootable)] [vmlinux] [kernel image]	ci-snapshot-upstream-root	UBSAN: shift-out-of-bounds in squashfs_bio_read
2025/04/19 17:16	upstream	8560697b23dc	2a20f901	.config	console log	report				[disk image (non-bootable)] [vmlinux] [kernel image]	ci-snapshot-upstream-root	UBSAN: shift-out-of-bounds in squashfs_bio_read
2025/04/06 03:12	upstream	56f944529ec2	1c65791e	.config	console log	report				[disk image (non-bootable)] [vmlinux] [kernel image]	ci-snapshot-upstream-root	UBSAN: shift-out-of-bounds in squashfs_bio_read

* ~~Struck through~~ repros no longer work on HEAD.