linux-kernel - Re: [PATCH v2] net/ipv4/tcp_cong: Replace strncpy() with strscpy()

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Message-ID: <20240715094107.GM8432@kernel.org>
Date: Mon, 15 Jul 2024 10:41:07 +0100
From: Simon Horman <horms@...nel.org>
To: Kees Cook <kees@...nel.org>
Cc: Eric Dumazet <edumazet@...gle.com>,
	"David S. Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>, Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v2] net/ipv4/tcp_cong: Replace strncpy() with strscpy()

On Sat, Jul 13, 2024 at 09:11:15PM -0700, Kees Cook wrote:
> Replace the deprecated[1] uses of strncpy() in tcp_ca_get_name_by_key()
> and tcp_get_default_congestion_control(). The callers use the results as
> standard C strings (via nla_put_string() and proc handlers respectively),
> so trailing padding is not needed.
> 
> Since passing the destination buffer arguments decays it to a pointer,
> the size can't be trivially determined by the compiler. ca->name is
> the same length in both cases, so strscpy() won't fail (when ca->name
> is NUL-terminated). Include the length explicitly instead of using the
> 2-argument strscpy().
> 
> Link: https://github.com/KSPP/linux/issues/90 [1]
> Signed-off-by: Kees Cook <kees@...nel.org>

nit: Looking at git history, the subject prefix should probably be 'tcp'.
     And it would be best to explicitly target the patch against net-next.

     Subject: [PATCH net-next v2] tcp: ...

That notwithstanding, this looks good to me.

Reviewed-by: Simon Horman <horms@...nel.org>

...