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

[David Laight <david.laight.linux@gmail.com>]

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.

	David

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