2022-12-23 02:55:54

by Yang Yang

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

From: Xu Panda <[email protected]>

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 <[email protected]>
Signed-off-by: Yang Yang <[email protected]>
---
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

2023-01-17 23:32:33

by Johannes Berg

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

On Fri, 2022-12-23 at 10:52 +0800, [email protected] wrote:
> From: Xu Panda <[email protected]>
>
> 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 <[email protected]>
> Signed-off-by: Yang Yang <[email protected]>
> ---
> 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

2023-01-18 02:30:29

by Yang Yang

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

> 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