[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>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 882cde4b4047..e3ec21695832 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++;