netdev - Re: Undefined behaviour of connect(fd, NULL, 0);

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Message-ID: <n2w412e6f7f1003312000o3a69802j120acd3946458517@mail.gmail.com>
Date:	Thu, 1 Apr 2010 11:00:23 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Neil Brown <neilb@...e.de>
Cc:	David Miller <davem@...emloft.net>, shemminger@...tta.com,
	netdev@...r.kernel.org
Subject: Re: Undefined behaviour of connect(fd, NULL, 0);

I think the following patch is what Neil wants. The old code implies that
connect(fd, NULL, 0) is used to check the socket connecting status, but
Stephen's patch breaks it. The old code is wrong when it checks the address's
faimly but not check the sizeof of the address to determine the family member
is valid or not before.

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index be1a6ac..3ff51f0 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -576,7 +576,8 @@ int inet_stream_connect(struct socket *sock,
struct sockaddr *uaddr,

 	lock_sock(sk);

-	if (uaddr->sa_family == AF_UNSPEC) {
+	if (addr_len >= sizeof(uaddr->sa_family) &&
+	    uaddr->sa_family == AF_UNSPEC) {
 		err = sk->sk_prot->disconnect(sk, flags);
 		sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
 		goto out;
--
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