[syzbot] [kernel?] UBSAN: shift-out-of-bounds in aio_iiro_16_attach

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a79a588fc176 Merge tag 'pm-6.16-rc5' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14a4ac8c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5ba6cef8f153bfeb
dashboard link: https://syzkaller.appspot.com/bug?extid=f1bb7e4ea47ea12b535c
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12a4ac8c580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13fc9c8c580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-a79a588f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c7aa4e6d68b0/vmlinux-a79a588f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5d71f2c64f29/bzImage-a79a588f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f1bb7e...@syzkaller.appspotmail.com

UBSAN: shift-out-of-bounds in drivers/comedi/drivers/aio_iiro_16.c:180:9
shift exponent 8550 is too large for 32-bit type 'int'
CPU: 2 UID: 0 PID: 6096 Comm: syz.0.16 Not tainted 6.16.0-rc4-syzkaller-00308-ga79a588fc176 #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+0x16c/0x1f0 lib/dump_stack.c:120
ubsan_epilogue lib/ubsan.c:233 [inline]
__ubsan_handle_shift_out_of_bounds+0x27f/0x420 lib/ubsan.c:494
aio_iiro_16_attach drivers/comedi/drivers/aio_iiro_16.c:180 [inline]
aio_iiro_16_attach.cold+0x19/0x1e drivers/comedi/drivers/aio_iiro_16.c:164
comedi_device_attach+0x3b3/0x900 drivers/comedi/drivers.c:996
do_devconfig_ioctl+0x1a7/0x580 drivers/comedi/comedi_fops.c:855
comedi_unlocked_ioctl+0x15bb/0x2e90 drivers/comedi/comedi_fops.c:2136
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl fs/ioctl.c:893 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:893
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3eb858e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc84ea1e58 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f3eb87b5fa0 RCX: 00007f3eb858e929
RDX: 0000200000000140 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f3eb8610b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f3eb87b5fa0 R14: 00007f3eb87b5fa0 R15: 0000000000000003
</TASK>
---[ end trace ]---


---
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[Edward Adam Davis]

#syz test

diff --git a/drivers/comedi/drivers/aio_iiro_16.c b/drivers/comedi/drivers/aio_iiro_16.c
index b00fab0b89d4..e43730f00c8b 100644
--- a/drivers/comedi/drivers/aio_iiro_16.c
+++ b/drivers/comedi/drivers/aio_iiro_16.c
@@ -177,7 +177,8 @@ static int aio_iiro_16_attach(struct comedi_device *dev,
* Digital input change of state interrupts are optionally supported
* using IRQ 2-7, 10-12, 14, or 15.
*/
- if ((1 << it->options[1]) & 0xdcfc) {
+ if (it->options[1] > 1 && it->options[1] < 16 &&
+ (1 << it->options[1]) & 0xdcfc) {
ret = request_irq(it->options[1], aio_iiro_16_cos, 0,
dev->board_name, dev);
if (ret == 0)

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+f1bb7e...@syzkaller.appspotmail.com
Tested-by: syzbot+f1bb7e...@syzkaller.appspotmail.com

Tested on:

commit: d7b8f8e2 Linux 6.16-rc5
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=121eabd4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a09d8660a55f005f

dashboard link: https://syzkaller.appspot.com/bug?extid=f1bb7e4ea47ea12b535c
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=12734a8c580000

Note: testing is done by a robot and is best-effort only.

[Edward Adam Davis]

The irq number 0x2166 passed by the reproducer is too large and is not
within the supported range [2-7, 10-12, 14, or 15], which triggers the oob.

Fixes: ad7a370c8be4 ("staging: comedi: aio_iiro_16: add command support for change of state detection")
Reported-by: syzbot+f1bb7e...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f1bb7e4ea47ea12b535c
Signed-off-by: Edward Adam Davis <ead...@qq.com>
---
drivers/comedi/drivers/aio_iiro_16.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--
2.43.0

[Ian Abbott]

The patch is fine apart from the misspelling of "invalid" in the subject
line, but I'd already submitted a patch for this before syzbot detected it:

https://lore.kernel.org/lkml/20250707134622....@mev.co.uk/

--
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-=( Regd. addr.: S11 & 12 Building 67, Europa Business Park, )=-
-=( Bird Hall Lane, STOCKPORT, SK3 0XA, UK. || www.mev.co.uk )=-

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: Re: [syzbot] [kernel?] UBSAN: shift-out-of-bounds in aio_iiro_16_attach
Author: xand...@gmail.com

> —[ end trace ]—
>
>
> —

> This report is generated by a bot. It may contain errors.
> See <https://goo.gl/tpsmEJ> for more information about syzbot.
> syzbot engineers can be reached at syzk...@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> <https://goo.gl/tpsmEJ#status> for how to communicate with syzbot.
>
> If the report is already addressed, let syzbot know by replying with:
> #syz fix: exact-commit-title
>
> 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.
>
> If you want to overwrite report’s subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
>
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
>
> If you want to undo deduplication, reply with:
> #syz undup

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 66acb1586737

[Abhinav Saxena]

Ian Abbott <abb...@mev.co.uk> writes:

> On 08/07/2025 13:37, Edward Adam Davis wrote:
>> The irq number 0x2166 passed by the reproducer is too large and is not
>> within the supported range [2-7, 10-12, 14, or 15], which triggers the oob.
>> Fixes: ad7a370c8be4 (“staging: comedi: aio_iiro_16: add command
>> support for change of state detection”)
>> Reported-by: syzbot+f1bb7e...@syzkaller.appspotmail.com
>> Closes: <https://syzkaller.appspot.com/bug?extid=f1bb7e4ea47ea12b535c>
>> Signed-off-by: Edward Adam Davis <ead...@qq.com>

>> —

>> drivers/comedi/drivers/aio_iiro_16.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)

>> diff –git a/drivers/comedi/drivers/aio_iiro_16.c
>> b/drivers/comedi/drivers/aio_iiro_16.c
>> index b00fab0b89d4..e43730f00c8b 100644
>> — a/drivers/comedi/drivers/aio_iiro_16.c

>> +++ b/drivers/comedi/drivers/aio_iiro_16.c
>> @@ -177,7 +177,8 @@ static int aio_iiro_16_attach(struct comedi_device *dev,
>> * Digital input change of state interrupts are optionally supported
>> * using IRQ 2-7, 10-12, 14, or 15.
>> */
>> - if ((1 << it->options[1]) & 0xdcfc) {
>> + if (it->options[1] > 1 && it->options[1] < 16 &&
>> + (1 << it->options[1]) & 0xdcfc) {
>> ret = request_irq(it->options[1], aio_iiro_16_cos, 0,
>> dev->board_name, dev);
>> if (ret == 0)
>
> The patch is fine apart from the misspelling of “invalid” in the subject
> line, but I’d already submitted a patch for this before syzbot detected
> it:
>
> <https://lore.kernel.org/lkml/20250707134622....@mev.co.uk/>

#syz fix: comedi: aio_iiro_16: Fix bit shift out of bounds