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From: Kees Cook <keescook@chromium.org>
To: laniel_francis@privacyrequired.com
Cc: linux-hardening@vger.kernel.org, netdev@vger.kernel.org,
	davem@davemloft.net, kuba@kernel.org
Subject: Re: [RFC][PATCH v3 1/3] Fix unefficient call to memset before memcpu in nla_strlcpy.
Date: Wed, 21 Oct 2020 16:46:23 -0700	[thread overview]
Message-ID: <202010211646.28D4C5642@keescook> (raw)
In-Reply-To: <20201020164707.30402-2-laniel_francis@privacyrequired.com>

On Tue, Oct 20, 2020 at 06:47:05PM +0200, laniel_francis@privacyrequired.com wrote:
> From: Francis Laniel <laniel_francis@privacyrequired.com>
> 
> 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 <laniel_francis@privacyrequired.com>

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

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

-- 
Kees Cook

  reply	other threads:[~2020-10-21 23:46 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-20 16:47 [RFC][PATCH v3 0/3] Fix inefficiences and rename nla_strlcpy laniel_francis
2020-10-20 16:47 ` [RFC][PATCH v3 1/3] Fix unefficient call to memset before memcpu in nla_strlcpy laniel_francis
2020-10-21 23:46   ` Kees Cook [this message]
2020-10-20 16:47 ` [RFC][PATCH v3 2/3] Modify return value of nla_strlcpy to match that of strscpy laniel_francis
2020-10-21 23:48   ` Kees Cook
2020-10-22  9:40     ` Francis Laniel
2020-10-20 16:47 ` [RFC][PATCH v3 3/3] Rename nla_strlcpy to nla_strscpy laniel_francis
2020-10-21 23:49   ` Kees Cook
2020-10-22  9:41     ` Francis Laniel
2020-10-22 20:04       ` Kees Cook
2020-10-22 23:05         ` Jakub Kicinski
2020-10-23  8:07           ` David Laight
2020-10-23 15:15             ` Francis Laniel
2020-10-23 15:29             ` Jakub Kicinski
2020-10-23 17:41               ` Kees Cook
2020-10-23 15:16           ` Francis Laniel
2020-10-24 10:41         ` Francis Laniel

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