wifi: airo: use strscpy() to instead of strncpy()

[PATCH net-next] wifi: airo: use strscpy() to instead of strncpy()

Posted by yang.yang29@zte.com.cn 2 years, 8 months ago

From: Xu Panda <xu.panda@zte.com.cn>

The implementation of strscpy() is more robust and safer.
That's now the recommended way to copy NUL-terminated strings.

Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
---
 drivers/net/wireless/cisco/airo.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/net/wireless/cisco/airo.c b/drivers/net/wireless/cisco/airo.c
index 7c4cc5f5e1eb..600a64f671ce 100644
--- a/drivers/net/wireless/cisco/airo.c
+++ b/drivers/net/wireless/cisco/airo.c
@@ -6067,8 +6067,7 @@ static int airo_get_nick(struct net_device *dev,
 	struct airo_info *local = dev->ml_priv;

 	readConfigRid(local, 1);
-	strncpy(extra, local->config.nodeName, 16);
-	extra[16] = '\0';
+	strscpy(extra, local->config.nodeName, 17);
 	dwrq->length = strlen(extra);

 	return 0;
-- 
2.15.2

Re: [PATCH net-next] wifi: airo: use strscpy() to instead of strncpy()

Posted by Johannes Berg 2 years, 8 months ago

On Fri, 2022-12-23 at 10:52 +0800, yang.yang29@zte.com.cn wrote:
> From: Xu Panda <xu.panda@zte.com.cn>
> 
> The implementation of strscpy() is more robust and safer.
> That's now the recommended way to copy NUL-terminated strings.
> 
> Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
> Signed-off-by: Yang Yang <yang.yang29@zte.com>
> ---
>  drivers/net/wireless/cisco/airo.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/drivers/net/wireless/cisco/airo.c b/drivers/net/wireless/cisco/airo.c
> index 7c4cc5f5e1eb..600a64f671ce 100644
> --- a/drivers/net/wireless/cisco/airo.c
> +++ b/drivers/net/wireless/cisco/airo.c
> @@ -6067,8 +6067,7 @@ static int airo_get_nick(struct net_device *dev,
>  	struct airo_info *local = dev->ml_priv;
> 
>  	readConfigRid(local, 1);
> -	strncpy(extra, local->config.nodeName, 16);
> -	extra[16] = '\0';
> +	strscpy(extra, local->config.nodeName, 17);
>  	dwrq->length = strlen(extra);
> 

Again, why bother. But is this even correct/identical behaviour?
Wouldn't it potentially read 17 input bytes before forcing NUL-
termination?

johannes

Re: [PATCH net-next] wifi: airo: use strscpy() to instead of strncpy()

Posted by yang.yang29@zte.com.cn 2 years, 8 months ago

> Again, why bother. But is this even correct/identical behaviour?>>
> Wouldn't it potentially read 17 input bytes before forcing NUL-
> termination?

Thank you for your reminder. This is a terrible error. Strscpy() may
cause the array to be out of bounds. I should be more cautious
next time.

Xu and Yang