[PATCH] mac80211: Replace strlcpy with strscpy

[PATCH] mac80211: 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 LOCAL_ASSIGN is only used by
TRACE macros and the return values are ignored.

[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/mac80211/trace.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/trace.h b/net/mac80211/trace.h
index db0d0132c58c..c51c6e3feac9 100644
--- a/net/mac80211/trace.h
+++ b/net/mac80211/trace.h
@@ -17,7 +17,7 @@
 
 #define MAXNAME		32
 #define LOCAL_ENTRY	__array(char, wiphy_name, 32)
-#define LOCAL_ASSIGN	strlcpy(__entry->wiphy_name, wiphy_name(local->hw.wiphy), MAXNAME)
+#define LOCAL_ASSIGN	strscpy(__entry->wiphy_name, wiphy_name(local->hw.wiphy), MAXNAME)
 #define LOCAL_PR_FMT	"%s"
 #define LOCAL_PR_ARG	__entry->wiphy_name
 
-- 
2.41.0.162.gfafddb0af9-goog

Re: [PATCH] mac80211: Replace strlcpy with strscpy

[Kees Cook]

On Tue, Jun 13, 2023 at 12:34:04AM +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 LOCAL_ASSIGN is only used by
> TRACE macros and the return values are ignored.
> 
> [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] mac80211: Replace strlcpy with strscpy

[Simon Horman]

On Tue, Jun 13, 2023 at 12:34:04AM +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 LOCAL_ASSIGN is only used by
> TRACE macros and the return values are ignored.
> 
> [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: Simon Horman <simon.horman@corigine.com>