netdev - Re: PATCH: uninitialized memory access in tcp_parse

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Message-Id: <20100628.212241.245398923.davem@davemloft.net>
Date:	Mon, 28 Jun 2010 21:22:41 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	mathieu.lacage@...hia.inria.fr, netdev@...r.kernel.org
Subject: Re: PATCH: uninitialized memory access in tcp_parse_options

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Sat, 26 Jun 2010 07:58:04 +0200

> If you want to avoid valgrind false positive at this point, without
> introducing bug for other tcp_parse_options() callers, a better fix
> would be following patch.
> 
> Thanks
> 
> diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
> index 794c2e1..4e758ac 100644
> --- a/net/ipv4/tcp_minisocks.c
> +++ b/net/ipv4/tcp_minisocks.c
> @@ -520,14 +520,13 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
>  			   struct request_sock *req,
>  			   struct request_sock **prev)
>  {
> -	struct tcp_options_received tmp_opt;
> +	struct tcp_options_received tmp_opt = {0};
>  	u8 *hash_location;
>  	struct sock *child;

That's a 28 byte memset() in the connect fast-path.  We shouldn't eat this
just to placate a valgrind miscue. :-)


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