[PATCH] wifi: mwifiex: Replace strlcpy with strscpy

[PATCH] wifi: mwifiex: 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>
---
 drivers/net/wireless/marvell/mwifiex/main.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/wireless/marvell/mwifiex/main.c b/drivers/net/wireless/marvell/mwifiex/main.c
index 1cd9d20cca16..8d3c4bcf9c89 100644
--- a/drivers/net/wireless/marvell/mwifiex/main.c
+++ b/drivers/net/wireless/marvell/mwifiex/main.c
@@ -725,9 +725,8 @@ static int mwifiex_init_hw_fw(struct mwifiex_adapter *adapter,
 	 * manufacturing mode is enabled
 	 */
 	if (mfg_mode) {
-		if (strlcpy(adapter->fw_name, MFG_FIRMWARE,
-			    sizeof(adapter->fw_name)) >=
-			    sizeof(adapter->fw_name)) {
+		if (strscpy(adapter->fw_name, MFG_FIRMWARE,
+			    sizeof(adapter->fw_name)) < 0) {
 			pr_err("%s: fw_name too long!\n", __func__);
 			return -1;
 		}
-- 
2.41.0.255.g8b1d071c50-goog

Re: [PATCH] wifi: mwifiex: Replace strlcpy with strscpy

[Kees Cook]

On Mon, Jul 10, 2023 at 03:06:25AM +0000, Azeem Shaikh 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>

Reviewed-by: Kees Cook <keescook@chromium.org>

-- 
Kees Cook

Re: [PATCH] wifi: mwifiex: Replace strlcpy with strscpy

[Kees Cook]

On Mon, 10 Jul 2023 03:06:25 +0000, Azeem Shaikh 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().
> 
> [...]

Applied, thanks!

[1/1] wifi: mwifiex: Replace strlcpy with strscpy
      https://git.kernel.org/kees/c/5469fb73e96d

Best regards,
-- 
Kees Cook

Re: [PATCH] wifi: mwifiex: Replace strlcpy with strscpy

[Kalle Valo]

Kees Cook <keescook@chromium.org> writes:

> On Mon, 10 Jul 2023 03:06:25 +0000, Azeem Shaikh 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().
>> 
>> [...]
>
> Applied, thanks!
>
> [1/1] wifi: mwifiex: Replace strlcpy with strscpy
>       https://git.kernel.org/kees/c/5469fb73e96d

And the same question here, why are you taking wifi patches without
acks? And this already fixed differently in wireless-next so our trees
conflict now:

https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git/commit/?id=caf9ead2c7d06fd7aa4cb48bd569ad61db9a0b4a

-- 
https://patchwork.kernel.org/project/linux-wireless/list/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH] wifi: mwifiex: Replace strlcpy with strscpy

[Kees Cook]

On Thu, Jul 27, 2023 at 07:02:31PM +0300, Kalle Valo wrote:
> Kees Cook <keescook@chromium.org> writes:
> 
> > On Mon, 10 Jul 2023 03:06:25 +0000, Azeem Shaikh 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().
> >> 
> >> [...]
> >
> > Applied, thanks!
> >
> > [1/1] wifi: mwifiex: Replace strlcpy with strscpy
> >       https://git.kernel.org/kees/c/5469fb73e96d
> 
> And the same question here, why are you taking wifi patches without
> acks? And this already fixed differently in wireless-next so our trees
> conflict now:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git/commit/?id=caf9ead2c7d06fd7aa4cb48bd569ad61db9a0b4a

Thanks for pointing that out! I saw no feedback on Azeem's patch, so it
looked like it was being ignored.

For the patch you linked to -- it's okay to have lost the overflow
detection and warning?

Regardless, I will drop this from my tree.

-Kees

-- 
Kees Cook

Re: [PATCH] wifi: mwifiex: Replace strlcpy with strscpy

[Brian Norris]

On Thu, Jul 27, 2023 at 10:04 AM Kees Cook <keescook@chromium.org> wrote:
>
> On Thu, Jul 27, 2023 at 07:02:31PM +0300, Kalle Valo wrote:
> > https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git/commit/?id=caf9ead2c7d06fd7aa4cb48bd569ad61db9a0b4a
>
> For the patch you linked to -- it's okay to have lost the overflow
> detection and warning?

It's a fixed constant string being copied into a larger fixed array.
It really doesn't matter functionality-wise. At best, the error check
would be useful for human readers or automated tools. So I didn't
bother complaining one way or another, as it took enough tries for the
submitter to get things right in the first place.

Brian

Re: [PATCH] wifi: mwifiex: Replace strlcpy with strscpy

[Kees Cook]

On Thu, Jul 27, 2023 at 10:30:29AM -0700, Brian Norris wrote:
> On Thu, Jul 27, 2023 at 10:04 AM Kees Cook <keescook@chromium.org> wrote:
> >
> > On Thu, Jul 27, 2023 at 07:02:31PM +0300, Kalle Valo wrote:
> > > https://git.kernel.org/pub/scm/linux/kernel/git/wireless/wireless-next.git/commit/?id=caf9ead2c7d06fd7aa4cb48bd569ad61db9a0b4a
> >
> > For the patch you linked to -- it's okay to have lost the overflow
> > detection and warning?
> 
> It's a fixed constant string being copied into a larger fixed array.
> It really doesn't matter functionality-wise. At best, the error check
> would be useful for human readers or automated tools. So I didn't
> bother complaining one way or another, as it took enough tries for the
> submitter to get things right in the first place.

Gotcha. Thanks!

-- 
Kees Cook