Subject: Re: [RFC][PATCH v3 1/3] Fix unefficient call to memset before memcpu in nla_strlcpy.

From: Kees Cook <[email-masked]>
Date: Wed, 21 Oct 2020 16:46:23 -0700

On Tue, Oct 20, 2020 at 06:47:05PM +0200, [email-masked] wrote:
> From: Francis Laniel <[email-masked]>
> 
> Before this commit, nla_strlcpy first memseted dst to 0 then wrote src into it.
> This is inefficient because bytes whom number is less than src length are written
> twice.
> 
> This patch solves this issue by first writing src into dst then fill dst with
> 0's.
> Note that, in the case where src length is higher than dst, only 0 is written.
> Otherwise there are as many 0's written to fill dst.
> 
> For example, if src is "foo\0" and dst is 5 bytes long, the result will be:
> 1. "fooGG" after memcpy (G means garbage).
> 2. "foo\0\0" after memset.
> 
> Signed-off-by: Francis Laniel <[email-masked]>

Looks good! (If there are future versions of this series, I think you
can drop the RFC part...)

Reviewed-by: Kees Cook <[email-masked]>

-- 
Kees Cook