[syzbot] [hwmon?] KMSAN: uninit-value in get_temp_cnct

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4774cfe3543a Merge tag 'scsi-fixes' of git://git.kernel.or..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10e3f10c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=61539536677af51c
dashboard link: https://syzkaller.appspot.com/bug?extid=3bbbade4e1a7ab45ca3b
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
userspace arch: i386

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/0cb38ba04f99/disk-4774cfe3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ff376a7ba200/vmlinux-4774cfe3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/570051315dbf/bzImage-4774cfe3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3bbbad...@syzkaller.appspotmail.com

usb 7-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 7-1: config 0 descriptor??
corsair-cpro 0003:1B1C:0C10.0017: hidraw0: USB HID v4.06 Device [HID 1b1c:0c10] on usb-dummy_hcd.6-1/input0
=====================================================
BUG: KMSAN: uninit-value in get_temp_cnct+0x1f3/0x3b0 drivers/hwmon/corsair-cpro.c:497
get_temp_cnct+0x1f3/0x3b0 drivers/hwmon/corsair-cpro.c:497
ccp_probe+0x458/0x790 drivers/hwmon/corsair-cpro.c:622
__hid_device_probe drivers/hid/hid-core.c:2724 [inline]
hid_device_probe+0x539/0xab0 drivers/hid/hid-core.c:2761
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
hid_add_device+0x5ed/0x7b0 drivers/hid/hid-core.c:2907
usbhid_probe+0x1fec/0x2660 drivers/hid/usbhid/hid-core.c:1435
usb_probe_interface+0xd04/0x1310 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
usb_set_configuration+0x3493/0x3b70 drivers/usb/core/message.c:2210
usb_generic_driver_probe+0xfc/0x290 drivers/usb/core/generic.c:250
usb_probe_device+0x38a/0x690 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
usb_new_device+0x104b/0x20c0 drivers/usb/core/hub.c:2663
hub_port_connect drivers/usb/core/hub.c:5535 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
port_event drivers/usb/core/hub.c:5835 [inline]
hub_event+0x5588/0x7580 drivers/usb/core/hub.c:5917
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
kthread+0xd5c/0xf00 kernel/kthread.c:464
ret_from_fork+0x1e0/0x310 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was stored to memory at:
get_temp_cnct+0x1ec/0x3b0 drivers/hwmon/corsair-cpro.c:496
ccp_probe+0x458/0x790 drivers/hwmon/corsair-cpro.c:622
__hid_device_probe drivers/hid/hid-core.c:2724 [inline]
hid_device_probe+0x539/0xab0 drivers/hid/hid-core.c:2761
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
hid_add_device+0x5ed/0x7b0 drivers/hid/hid-core.c:2907
usbhid_probe+0x1fec/0x2660 drivers/hid/usbhid/hid-core.c:1435
usb_probe_interface+0xd04/0x1310 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
usb_set_configuration+0x3493/0x3b70 drivers/usb/core/message.c:2210
usb_generic_driver_probe+0xfc/0x290 drivers/usb/core/generic.c:250
usb_probe_device+0x38a/0x690 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
usb_new_device+0x104b/0x20c0 drivers/usb/core/hub.c:2663
hub_port_connect drivers/usb/core/hub.c:5535 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
port_event drivers/usb/core/hub.c:5835 [inline]
hub_event+0x5588/0x7580 drivers/usb/core/hub.c:5917
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
kthread+0xd5c/0xf00 kernel/kthread.c:464
ret_from_fork+0x1e0/0x310 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was created at:
slab_post_alloc_hook mm/slub.c:4154 [inline]
slab_alloc_node mm/slub.c:4197 [inline]
__do_kmalloc_node mm/slub.c:4327 [inline]
__kmalloc_node_track_caller_noprof+0x96d/0x12f0 mm/slub.c:4347
alloc_dr drivers/base/devres.c:119 [inline]
devm_kmalloc+0xd7/0x2f0 drivers/base/devres.c:864
ccp_probe+0x114/0x790 drivers/hwmon/corsair-cpro.c:596
__hid_device_probe drivers/hid/hid-core.c:2724 [inline]
hid_device_probe+0x539/0xab0 drivers/hid/hid-core.c:2761
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
hid_add_device+0x5ed/0x7b0 drivers/hid/hid-core.c:2907
usbhid_probe+0x1fec/0x2660 drivers/hid/usbhid/hid-core.c:1435
usb_probe_interface+0xd04/0x1310 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
usb_set_configuration+0x3493/0x3b70 drivers/usb/core/message.c:2210
usb_generic_driver_probe+0xfc/0x290 drivers/usb/core/generic.c:250
usb_probe_device+0x38a/0x690 drivers/usb/core/driver.c:291
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x4d4/0xd90 drivers/base/dd.c:657
__driver_probe_device+0x268/0x380 drivers/base/dd.c:799
driver_probe_device+0x70/0x8b0 drivers/base/dd.c:829
__device_attach_driver+0x4ee/0x950 drivers/base/dd.c:957
bus_for_each_drv+0x3e0/0x680 drivers/base/bus.c:462
__device_attach+0x3c8/0x5c0 drivers/base/dd.c:1029
device_initial_probe+0x33/0x40 drivers/base/dd.c:1078
bus_probe_device+0x3ba/0x5e0 drivers/base/bus.c:537
device_add+0x12a9/0x1c10 drivers/base/core.c:3692
usb_new_device+0x104b/0x20c0 drivers/usb/core/hub.c:2663
hub_port_connect drivers/usb/core/hub.c:5535 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5675 [inline]
port_event drivers/usb/core/hub.c:5835 [inline]
hub_event+0x5588/0x7580 drivers/usb/core/hub.c:5917
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xb91/0x1d80 kernel/workqueue.c:3321
worker_thread+0xedf/0x1590 kernel/workqueue.c:3402
kthread+0xd5c/0xf00 kernel/kthread.c:464
ret_from_fork+0x1e0/0x310 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

CPU: 0 UID: 0 PID: 5855 Comm: kworker/0:3 Not tainted 6.16.0-rc1-syzkaller-00203-g4774cfe3543a #0 PREEMPT(undef)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: usb_hub_wq hub_event
=====================================================


---
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[Guenter Roeck]

On 6/18/25 21:31, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 4774cfe3543a Merge tag 'scsi-fixes' of git://git.kernel.or..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=10e3f10c580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=61539536677af51c
> dashboard link: https://syzkaller.appspot.com/bug?extid=3bbbade4e1a7ab45ca3b
> compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
> userspace arch: i386
>
> Unfortunately, I don't have any reproducer for this issue yet.
>

It doesn't need one: The problem will be seen if the data returned from the
power supply is shorter than expected. In the example below, the problem will
be seen if less than NUM_TEMP_SENSORS+1 data bytes were received.
One possible fix would be to record the returned data length in ccp_raw_event()
and to have each caller of send_usb_cmd() check if the returned amount of data
is sufficient.

Guenter

[Marius Zachmann]

The device should always return the same number of bytes.
I could zero-initialize the buffer at allocation. Then there should
be no uninitialized values.
Also I could check the number of returned bytes in send_usb_cmd()
instead of having each caller checking it, and return -EIO if
it is not correct?

Marius

[Guenter Roeck]

The term is "should". That doesn't mean it always _does_ return the
expected number of bytes, only that it is expected to do so.

> I could zero-initialize the buffer at allocation. Then there should
> be no uninitialized values.

As long as the values are usable, sure. That would not really fix the
protocol error, though, it would just hide it.

> Also I could check the number of returned bytes in send_usb_cmd()
> instead of having each caller checking it, and return -EIO if
> it is not correct?
>

Yes, that would be an even better fix, though I would suggest to return
-EPROTO in that case to distinguish it from an actual i/o error.

Thanks,
Guenter

[Edward Adam Davis]

When the data size returned by the sensor is less than IN_BUFFER_SIZE,
it is padded with 0.

Reported-by: syzbot+3bbbad...@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3bbbade4e1a7ab45ca3b
Signed-off-by: Edward Adam Davis <ead...@qq.com>
---
drivers/hwmon/corsair-cpro.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/hwmon/corsair-cpro.c b/drivers/hwmon/corsair-cpro.c
index e1a7f7aa7f80..274864e8a8e7 100644
--- a/drivers/hwmon/corsair-cpro.c
+++ b/drivers/hwmon/corsair-cpro.c
@@ -157,6 +157,8 @@ static int ccp_raw_event(struct hid_device *hdev, struct hid_report *report, u8
spin_lock(&ccp->wait_input_report_lock);
if (!completion_done(&ccp->wait_input_report)) {
memcpy(ccp->buffer, data, min(IN_BUFFER_SIZE, size));
+ if (size < IN_BUFFER_SIZE)
+ memset(ccp->buffer + size, 0, IN_BUFFER_SIZE - size);
complete_all(&ccp->wait_input_report);
}
spin_unlock(&ccp->wait_input_report_lock);
--
2.43.0

[Guenter Roeck]

On 6/19/25 06:37, Edward Adam Davis wrote:
> When the data size returned by the sensor is less than IN_BUFFER_SIZE,
> it is padded with 0.
>

The subject is missing the affected driver, and I really very much prefer
actually validating the return data instead of just assuming that it is
ok to fill the buffer with 0. So I'll take Marius' patch instead.

On a side note, please don't send patches as reply to some other e-mail.
That only asks for it to get lost.

Thanks,
Guenter