From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Thu, 6 Sep 2007 13:06:35 +0000 (+0100)
Subject: [NET]: Do not dereference iov if length is zero
X-Git-Tag: v2.6.23-rc7~100^2~9
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ef8aef55ce61fd0e2af798695f7386ac756ae1e7;p=linux-2.6

[NET]: Do not dereference iov if length is zero

When msg_iovlen is zero we shouldn't try to dereference
msg_iov.  Right now the only thing that tries to do so
is skb_copy_and_csum_datagram_iovec.  Since the total
length should also be zero if msg_iovlen is zero, it's
sufficient to check the total length there and simply
return if it's zero.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/core/datagram.c b/net/core/datagram.c
index cb056f4761..029b93e246 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -450,6 +450,9 @@ int skb_copy_and_csum_datagram_iovec(struct sk_buff *skb,
 	__wsum csum;
 	int chunk = skb->len - hlen;
 
+	if (!chunk)
+		return 0;
+
 	/* Skip filled elements.
 	 * Pretty silly, look at memcpy_toiovec, though 8)
 	 */