From: Neil Horman <nhorman@redhat.com>
Subject: [RHEL 5.1 PATCH] igmp: check for NULL return when allocating skbs with GFP_ATOMIC
Date: Tue, 28 Aug 2007 16:20:33 -0400
Bugzilla: 252404
Message-Id: <20070828202033.GA14602@hmsendeavour.rdu.redhat.com>
Changelog: [net] igmp: check for NULL when allocating GFP_ATOMIC skbs


Hey-
	Backport of commit:
cc63f70b8b410eb653449151821f6b8b9af6ca42
Which verifies that add_grhead managed to allocate an skb, avoiding an oops on
dereference in the event that it didn't.  Fixes bz 252404

Regards
Neil


commit cc63f70b8b410eb653449151821f6b8b9af6ca42
Author: Alexey Dobriyan <adobriyan@openvz.org>

    [IPV4/IPV6] multicast: Check add_grhead() return value
    
    add_grhead() allocates memory with GFP_ATOMIC and in at least two places skb
    from it passed to skb_put() without checking.
    
    Signed-off-by: Alexey Dobriyan <adobriyan@openvz.org>
    Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 0017ccb..024ae56 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -455,6 +455,8 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ip_mc_list *pmc,
 			skb = add_grhead(skb, pmc, type, &pgr);
 			first = 0;
 		}
+		if (!skb)
+			return NULL;
 		psrc = (u32 *)skb_put(skb, sizeof(u32));
 		*psrc = psf->sf_inaddr;
 		scount++; stotal++;
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 882cde4..e3ec216 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1582,6 +1582,8 @@ static struct sk_buff *add_grec(struct sk_buff *skb, struct ifmcaddr6 *pmc,
 			skb = add_grhead(skb, pmc, type, &pgr);
 			first = 0;
 		}
+		if (!skb)
+			return NULL;
 		psrc = (struct in6_addr *)skb_put(skb, sizeof(*psrc));
 		*psrc = psf->sf_addr;
 		scount++; stotal++;
-- 
/***************************************************
 *Neil Horman
 *Software Engineer
 *Red Hat, Inc.
 *nhorman@redhat.com
 *gpg keyid: 1024D / 0x92A74FA1
 *http://pgp.mit.edu
 ***************************************************/