Re: [PATCH] HID: hid-steam: fix uninit-value access in steam_get_serial

[Pei Xiao]

在 2026/8/4 04:39, Vicki Pfau 写道:
> Hi Jiri,
> 
> On 8/3/26 12:34 PM, Jiri Kosina wrote:
>> CCing Vicki Pfau here ... could you please give your Ack to this fix?
> 
> This was already fixed in 9f8ee99f831b2711624ef81d0abba1d183f28b09 in the series I submitted earlier. I didn't realize there was an open bug report for it.
Hi maintainer and Vicki,
I took a look at this commit. In fact, my patch was nearly two months
earlier than this commit. I had originally thought that this one-line
patch, especially for an error-path case, had been ignored by the
maintainer.

thanks！
Pei.
> 
>>
>> Thanks.
>>
>> On Wed, 10 Jun 2026, Pei Xiao wrote:
>>
>>> The reply buffer in steam_get_serial() is allocated on the stack without
>>> initialization. In cases where steam_recv_report() returns a short read or
>>> an error, not all bytes of the buffer are written, leading to subsequent
>>> access of uninitialized memory when checking reply[0], reply[1], reply[2].
>>>
>>> Zero-initialize the reply array to prevent KMSAN uninit-value warnings.
>>>
>>> Logs:
>>> hid-steam 0003:28DE:1102.0007: unknown main item tag 0x0
>>> hid-steam 0003:28DE:1102.0007: unknown main item tag 0x0
>>> hid-steam 0003:28DE:1102.0007: :
>>> USB HID v7f.fd Device [HID 28de:1102] on usb-dummy_hcd.1-1/input0
>>> =====================================================
>>> BUG: KMSAN: uninit-value in steam_get_serial drivers/hid/hid-steam.c:457 [inline]
>>> BUG: KMSAN: uninit-value in steam_register+0xd83/0x10e0 drivers/hid/hid-steam.c:965
>>>  steam_get_serial drivers/hid/hid-steam.c:457 [inline]
>>>  steam_register+0xd83/0x10e0 drivers/hid/hid-steam.c:965
>>>  steam_probe+0x6f1/0x19b0 drivers/hid/hid-steam.c:1273
>>>  __hid_device_probe drivers/hid/hid-core.c:2822 [inline]
>>>  hid_device_probe+0x60d/0xb90 drivers/hid/hid-core.c:2859
>>>  call_driver_probe drivers/base/dd.c:-1 [inline]
>>>  really_probe+0x4d5/0xe40 drivers/base/dd.c:709
>>>  ...
>>>
>>> Local variable reply.i created at:
>>>  steam_get_serial drivers/hid/hid-steam.c:448 [inline]
>>>  steam_register+0x180/0x10e0 drivers/hid/hid-steam.c:965
>>>  steam_probe+0x6f1/0x19b0 drivers/hid/hid-steam.c:1273
>>>
>>> Reported-by: syzbot+75f3f9bff8c510602d36@xxxxxxxxxxxxxxxxxxxxxxxxx
>>> Closes: https://lore.kernel.org/lkml/6a27d055.39669fcc.33b062.008d.GAE@xxxxxxxxxx/
>>> Fixes: c164d6abf384 ("HID: add driver for Valve Steam Controller")
>>> Signed-off-by: Pei Xiao <xiaopei01@xxxxxxxxxx>
>>
>>
>>
>>> ---
>>>  drivers/hid/hid-steam.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/hid/hid-steam.c b/drivers/hid/hid-steam.c
>>> index 197126d6e081..f65ad1a21c01 100644
>>> --- a/drivers/hid/hid-steam.c
>>> +++ b/drivers/hid/hid-steam.c
>>> @@ -445,7 +445,7 @@ static int steam_get_serial(struct steam_device *steam)
>>>  	 */
>>>  	int ret = 0;
>>>  	u8 cmd[] = {ID_GET_STRING_ATTRIBUTE, sizeof(steam->serial_no), ATTRIB_STR_UNIT_SERIAL};
>>> -	u8 reply[3 + STEAM_SERIAL_LEN + 1];
>>> +	u8 reply[3 + STEAM_SERIAL_LEN + 1] = { 0 };
>>>  
>>>  	mutex_lock(&steam->report_mutex);
>>>  	ret = steam_send_report(steam, cmd, sizeof(cmd));
>>> -- 
>>> 2.25.1
>>>
>>
> 
> Vicki