[PATCH] bridge: fix a possible use after free
From: Eric Dumazet <hidden>
Date: 2011-08-24 05:57:09
br_multicast_ipv6_rcv() can call pskb_trim_rcsum() and therefore skb head can be reallocated. Cache icmp6_type field instead of dereferencing twice the struct icmp6hdr pointer. Signed-off-by: Eric Dumazet <redacted> --- net/bridge/br_multicast.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 2d85ca7..5db95fd 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c@@ -1456,7 +1456,7 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br, { struct sk_buff *skb2; const struct ipv6hdr *ip6h; - struct icmp6hdr *icmp6h; + u8 icmp6_type; u8 nexthdr; unsigned len; int offset;
@@ -1502,9 +1502,9 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br, __skb_pull(skb2, offset); skb_reset_transport_header(skb2); - icmp6h = icmp6_hdr(skb2); + icmp6_type = icmp6_hdr(skb2)->icmp6_type; - switch (icmp6h->icmp6_type) { + switch (icmp6_type) { case ICMPV6_MGM_QUERY: case ICMPV6_MGM_REPORT: case ICMPV6_MGM_REDUCTION:
@@ -1537,7 +1537,7 @@ static int br_multicast_ipv6_rcv(struct net_bridge *br, BR_INPUT_SKB_CB(skb)->igmp = 1; - switch (icmp6h->icmp6_type) { + switch (icmp6_type) { case ICMPV6_MGM_REPORT: { struct mld_msg *mld;