[syzbot] [comedi?] UBSAN: shift-out-of-bounds in dt2811_attach

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    93f51579e7df Linux 7.3-rc4
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17b45005580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=7d012d9c67977ee4
dashboard link: https://syzkaller.appspot.com/bug?extid=a4cedab706d0a8a3f988
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=106ff005580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10d054c9580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-93f51579.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/00f02ade84ed/vmlinux-93f51579.xz
kernel image: https://storage.googleapis.com/syzbot-assets/93be890b3b79/bzImage-93f51579.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a4cedab706d0a8a3f988@xxxxxxxxxxxxxxxxxxxxxxxxx

------------[ cut here ]------------
UBSAN: shift-out-of-bounds in drivers/comedi/drivers/dt2811.c:570:31
shift exponent -251 is negative
CPU: 0 UID: 0 PID: 5925 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x279/0x2a0 lib/ubsan.c:494
 dt2811_attach.cold+0x19/0x1e drivers/comedi/drivers/dt2811.c:570
 comedi_device_attach+0x40e/0x6b0 drivers/comedi/drivers.c:1101
 do_devconfig_ioctl+0x1b3/0x6d0 drivers/comedi/comedi_fops.c:930
 comedi_unlocked_ioctl+0x860/0x3310 drivers/comedi/comedi_fops.c:2302
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe50959e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffcc3e899c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fe509825fa0 RCX: 00007fe50959e159
RDX: 0000200000000100 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007fe50963506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe509825fac R14: 00007fe509825fa0 R15: 00007fe509825fa0
 </TASK>
---[ end trace ]---


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