Re: [PATCH] usb: typec: tcpm: replace strcpy with strscpy

[Amit Sunil Dhamne <amitsd@google.com>]

Hi David,

On 4/29/26 1:54 AM, David Laight wrote:
> On Thu, 23 Apr 2026 12:23:09 -0700
> Amit Sunil Dhamne <amitsd@google.com> wrote:
>
>> Hi Maxwell,
>>
>> On 4/19/26 2:36 PM, Maxwell Doose wrote:
>>> The function strcpy() is deprecated as it can be used in buffer overflow
>>> attacks. This patch replaces strcpy() with strscpy() to improve
>>> security and stability.
>>>
>>> Signed-off-by: Maxwell Doose <m32285159@gmail.com>
>>> ---
>>>   drivers/usb/typec/tcpm/tcpm.c | 6 +++---
>>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
>>> index 8e0e14a2704e..69574c5e79e1 100644
>>> --- a/drivers/usb/typec/tcpm/tcpm.c
>>> +++ b/drivers/usb/typec/tcpm/tcpm.c
>>> @@ -725,7 +725,7 @@ static void _tcpm_log(struct tcpm_port *port, const char *fmt, va_list args)
>>>   
>>>   	if (tcpm_log_full(port)) {
>>>   		port->logbuffer_head = max(port->logbuffer_head - 1, 0);
>>> -		strcpy(tmpbuffer, "overflow");
>>> +		strscpy(tmpbuffer, "overflow", sizeof(tmpbuffer))
>>>   	}
>>>   
>>>   	if (port->logbuffer_head < 0 ||
>>> @@ -841,10 +841,10 @@ static void tcpm_log_source_caps(struct tcpm_port *port)
>>>   					  pdo_spr_avs_apdo_15v_to_20v_max_current_ma(pdo),
>>>   					  pdo_spr_avs_apdo_src_peak_current(pdo));
>>>   			else
>>> -				strcpy(msg, "undefined APDO");
>>> +				strscpy(msg, "undefined APDO", sizeof(msg));
>>>   			break;
>>>   		default:
>>> -			strcpy(msg, "undefined");
>>> +			strscpy(msg, "undefined", sizeof(msg));
>>>   			break;
>>>   		}
>>>   		tcpm_log(port, " PDO %d: type %d, %s",  
>> This has already been fixed as part of [1].
> It is also 'not a fix'.
> strcpy() is fine for copying literal strings into arrays.
> With the kernel headers you get a compile error from strcpy() if the string
> is too long.
> OTOH strscpy() will truncate overlong strings.

Thanks for the explanation :) .


> 	David
>
>> [1] https://patch.msgid.link/20260310094434.3639602-5-aichao@kylinos.cn
>>
>>
>> BR,
>>
>> Amit
>>
>>