[PATCH] net: sched: Replace strlcpy with strscpy

[PATCH] net: sched: Replace strlcpy with strscpy

[Azeem Shaikh]

strlcpy() reads the entire source buffer first.
This read may exceed the destination size limit.
This is both inefficient and can lead to linear read
overflows if a source string is not NUL-terminated [1].
In an effort to remove strlcpy() completely [2], replace
strlcpy() here with strscpy().

Direct replacement is safe here since return value of -errno
is used to check for truncation instead of sizeof(dest).

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
[2] https://github.com/KSPP/linux/issues/89

Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
---
 net/sched/act_api.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index f7887f42d542..9d3f26bf0440 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -1320,7 +1320,7 @@ struct tc_action_ops *tc_action_load_ops(struct nlattr *nla, bool police,
 			return ERR_PTR(err);
 		}
 	} else {
-		if (strlcpy(act_name, "police", IFNAMSIZ) >= IFNAMSIZ) {
+		if (strscpy(act_name, "police", IFNAMSIZ) < 0) {
 			NL_SET_ERR_MSG(extack, "TC action name too long");
 			return ERR_PTR(-EINVAL);
 		}
-- 
2.41.0.255.g8b1d071c50-goog

Re: [PATCH] net: sched: Replace strlcpy with strscpy

[Pavan Chebbi]

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On Mon, Jul 10, 2023 at 8:37 AM Azeem Shaikh <azeemshaikh38@gmail.com> wrote:
>
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
>
> Direct replacement is safe here since return value of -errno
> is used to check for truncation instead of sizeof(dest).
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy
> [2] https://github.com/KSPP/linux/issues/89
>
> Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com>
> ---

Looks good to me.
Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>

>  net/sched/act_api.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sched/act_api.c b/net/sched/act_api.c
> index f7887f42d542..9d3f26bf0440 100644
> --- a/net/sched/act_api.c
> +++ b/net/sched/act_api.c
> @@ -1320,7 +1320,7 @@ struct tc_action_ops *tc_action_load_ops(struct nlattr *nla, bool police,
>                         return ERR_PTR(err);
>                 }
>         } else {
> -               if (strlcpy(act_name, "police", IFNAMSIZ) >= IFNAMSIZ) {
> +               if (strscpy(act_name, "police", IFNAMSIZ) < 0) {
>                         NL_SET_ERR_MSG(extack, "TC action name too long");
>                         return ERR_PTR(-EINVAL);
>                 }
> --
> 2.41.0.255.g8b1d071c50-goog
>
>
>

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Re: [PATCH] net: sched: Replace strlcpy with strscpy

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Mon, 10 Jul 2023 03:07:11 +0000 you wrote:
> strlcpy() reads the entire source buffer first.
> This read may exceed the destination size limit.
> This is both inefficient and can lead to linear read
> overflows if a source string is not NUL-terminated [1].
> In an effort to remove strlcpy() completely [2], replace
> strlcpy() here with strscpy().
> 
> [...]

Here is the summary with links:
  - net: sched: Replace strlcpy with strscpy
    https://git.kernel.org/netdev/net/c/989b52cdc849

You are awesome, thank you!
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