cx231xx: card->driver "Conexant cx231xx Audio" too long

card->driver is 15 characters and a NULL, the original code could cause a buffer overflow.

Signed-off-by Dan Carpenter <[email protected]>

drivers/media/video/cx231xx/cx231xx-audio.c +1 -2

index 7793d60..b3282ae 100644
@@ -495,7 +495,7 @@ static int cx231xx_audio_init(struct cx231xx *dev)
 	pcm->info_flags = 0;
 	pcm->private_data = dev;
 	strcpy(pcm->name, "Conexant cx231xx Capture");
-	strcpy(card->driver, "Conexant cx231xx Audio");
+	strcpy(card->driver, "Cx231xx Audio");
 	strcpy(card->shortname, "Cx231xx Audio");
 	strcpy(card->longname, "Conexant cx231xx Audio");
 
--

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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.

Quoted 4 lines · Dan Carpenter

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.

At Mon, 22 Mar 2010 08:43:47 -0700,

Quoted 8 lines · Joe Perches

Quoted 4 lines · Dan Carpenter

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

Quoted 25 lines · Takashi Iwai

At Mon, 22 Mar 2010 08:43:47 -0700,

Quoted 8 lines · Joe Perches

Quoted 4 lines · Dan Carpenter

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)

Quoted 9 lines

and used like:

struct foo {
	char foo[5];
} x;

COPY_STRING(x.foo, "OK"); // OK
COPY_STRING(x.foo, "1234567890"); // NG

I can do the same thing with Smatch. The smatch check can also find bugs like this:

	buf = kmalloc(10, GFP_KERNEL);
	strcpy(buf, "1234567890"); 

I used smatch to find this bug and 5 others on my allmodconfig w/ staging. I also found 19 other places that use strcpy() to copy from a large buffer into a smaller buffer.

Your idea is nice, but I think anyone who deliberately uses the new macro is not going to have the bug in the first place. ;)

At Mon, 22 Mar 2010 08:43:47 -0700,

Quoted 5 lines · Joe Perches

Quoted 3 lines · Dan Carpenter

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
--

Quoted 32 lines · Takashi Iwai

At Mon, 22 Mar 2010 08:43:47 -0700,

Quoted 5 lines · Joe Perches

Quoted 3 lines · Dan Carpenter

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

Quoted 2 lines

Takashi
--

did i miss something ?

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

At Mon, 22 Mar 2010 18:18:04 +0100,

Quoted 37 lines · walter harms

Quoted 33 lines · Takashi Iwai

At Mon, 22 Mar 2010 08:43:47 -0700,

Quoted 5 lines · Joe Perches

Quoted 3 lines · Dan Carpenter

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
--

Quoted 1 line

did i miss something ?

Yes :)

Quoted 2 lines

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.

card->driver is 15 characters and a NULL, the original code could cause a buffer overflow.

Signed-off-by Dan Carpenter <[email protected]>

---
In version 2, I used a better name that Takashi Iwai suggested.

drivers/media/video/cx231xx/cx231xx-audio.c +1 -2

index 7793d60..7cae95a 100644
@@ -495,7 +495,7 @@ static int cx231xx_audio_init(struct cx231xx *dev)
 	pcm->info_flags = 0;
 	pcm->private_data = dev;
 	strcpy(pcm->name, "Conexant cx231xx Capture");
-	strcpy(card->driver, "Conexant cx231xx Audio");
+	strcpy(card->driver, "Cx231xx-Audio");
 	strcpy(card->shortname, "Cx231xx Audio");
 	strcpy(card->longname, "Conexant cx231xx Audio");
 
--

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

At Mon, 22 Mar 2010 08:43:47 -0700,

Quoted 8 lines · Joe Perches

Quoted 4 lines · Dan Carpenter

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