[PATCH] ARM: s3c: Use strscpy to replace strlcpy

[PATCH] ARM: s3c: Use strscpy to replace strlcpy

[Jason Wang]

The strlcpy should not be used because it doesn't limit the source
length. As linus says, it's a completely useless function if you
can't implicitly trust the source string - but that is almost always
why people think they should use it! All in all the BSD function
will lead some potential bugs.

But the strscpy doesn't require reading memory from the src string
beyond the specified "count" bytes, and since the return value is
easier to error-check than strlcpy()'s. In addition, the implementation
is robust to the string changing out from underneath it, unlike the
current strlcpy() implementation.

Thus, We prefer using strscpy instead of strlcpy.

Signed-off-by: Jason Wang <wangborong@cdjrlc.com>
---
 arch/arm/mach-s3c/mach-mini6410.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/mach-s3c/mach-mini6410.c b/arch/arm/mach-s3c/mach-mini6410.c
index 741fa1f09694..c14c2e27127b 100644
--- a/arch/arm/mach-s3c/mach-mini6410.c
+++ b/arch/arm/mach-s3c/mach-mini6410.c
@@ -262,7 +262,7 @@ static char mini6410_features_str[12] __initdata = "0";
 static int __init mini6410_features_setup(char *str)
 {
 	if (str)
-		strlcpy(mini6410_features_str, str,
+		strscpy(mini6410_features_str, str,
 			sizeof(mini6410_features_str));
 	return 1;
 }
-- 
2.33.0

Re: [PATCH] ARM: s3c: Use strscpy to replace strlcpy

[Krzysztof Kozlowski]

On 06/09/2021 15:46, Jason Wang wrote:
> The strlcpy should not be used because it doesn't limit the source
> length. As linus says, it's a completely useless function if you
> can't implicitly trust the source string - but that is almost always
> why people think they should use it! All in all the BSD function
> will lead some potential bugs.
> 
> But the strscpy doesn't require reading memory from the src string
> beyond the specified "count" bytes, and since the return value is
> easier to error-check than strlcpy()'s. In addition, the implementation
> is robust to the string changing out from underneath it, unlike the
> current strlcpy() implementation.
> 
> Thus, We prefer using strscpy instead of strlcpy.

Don't copy-paste kernel documentation into commits. It's enough to say
that strlcpy is preferred, according to the kernel coding style (see
strlcpy()).

If you want to add more sentences, make them relevant, e.g. describe
possible effect of bugs depending on the source.




Best regards,
Krzysztof

Re: [PATCH] ARM: s3c: Use strscpy to replace strlcpy

[Krzysztof Kozlowski]

On Mon, 6 Sep 2021 21:46:56 +0800, Jason Wang wrote:
> The strlcpy should not be used because it doesn't limit the source
> length. As linus says, it's a completely useless function if you
> can't implicitly trust the source string - but that is almost always
> why people think they should use it! All in all the BSD function
> will lead some potential bugs.
> 
> But the strscpy doesn't require reading memory from the src string
> beyond the specified "count" bytes, and since the return value is
> easier to error-check than strlcpy()'s. In addition, the implementation
> is robust to the string changing out from underneath it, unlike the
> current strlcpy() implementation.
> 
> [...]

Applied, thanks!

[1/1] ARM: s3c: Use strscpy to replace strlcpy
      commit: aa519471715ce73034ffaa52fc85681de31c1acf

Best regards,
-- 
Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>