netdev - Re: [PATCH] net: recvmsg: Unconditionally zero struct sockaddr

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Message-ID: <20171101064954.GC1585@1wt.eu>
Date:   Wed, 1 Nov 2017 07:49:54 +0100
From:   Willy Tarreau <w@....eu>
To:     Kees Cook <keescook@...omium.org>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Alexander Potapenko <glider@...gle.com>,
        Kostya Serebryany <kcc@...gle.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, security@...nel.org
Subject: Re: [PATCH] net: recvmsg: Unconditionally zero struct
 sockaddr_storage

On Tue, Oct 31, 2017 at 09:14:45AM -0700, Kees Cook wrote:
> diff --git a/net/socket.c b/net/socket.c
> index c729625eb5d3..34183f4fbdf8 100644
> --- a/net/socket.c
> +++ b/net/socket.c
> @@ -2188,6 +2188,7 @@ static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
>  	struct sockaddr __user *uaddr;
>  	int __user *uaddr_len = COMPAT_NAMELEN(msg);
>  
> +	memset(&addr, 0, sizeof(addr));
>  	msg_sys->msg_name = &addr;

Isn't this going to cause a performance hit in the fast path ? Just
checking, I have not read the whole code with the patch in its context.

Willy