Re: [patch v2] cx231xx: card->driver "Conexant cx231xx Audio" too long

[Takashi Iwai <tiwai@suse.de>]

At Mon, 22 Mar 2010 18:18:04 +0100,
walter harms wrote:
> 
> 
> 
> Takashi Iwai schrieb:
> > At Mon, 22 Mar 2010 08:43:47 -0700,
> > Joe Perches wrote:
> >> On Mon, 2010-03-22 at 18:39 +0300, Dan Carpenter wrote:
> >>> card->driver is 15 characters and a NULL, the original code could 
> >>> cause a buffer overflow.
> >>> In version 2, I used a better name that Takashi Iwai suggested.
> >> Perhaps it's better to use strncpy as well.
> > 
> > strlcpy() would be safer :)
> > 
> > But, in such a case, we want rather that the error is notified at
> > build time.
> > 
> > Maybe a macro like below would be helpful to catch such bugs?
> > 
> > #define COPY_STRING(buf, src)						\
> > 	do {								\
> > 		if (__builtin_constant_p(src))				\
> > 			BUILD_BUG_ON(strlen(src) >= sizeof(buf));	\
> > 		strcpy(buf, src);					\
> > 	} while (0)
> > 
> > and used like:
> > 
> > struct foo {
> > 	char foo[5];
> > } x;
> > 
> > COPY_STRING(x.foo, "OK"); // OK
> > COPY_STRING(x.foo, "1234567890"); // NG
> > 
> > 
> > Takashi
> > --
> 
> 
> did i miss something ?

Yes :)

> why not change  card->driver int char * ? a simple card->driver="name"
> would solve the problem.

The length is fixed because it's used for ioctl.


Takashi