bridge: fix a possible use after free
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 <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 22d2d1a..995cbe0 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1456,7 +1456,7 @@
{
struct sk_buff *skb2;
const struct ipv6hdr *ip6h;
- struct icmp6hdr *icmp6h;
+ u8 icmp6_type;
u8 nexthdr;
unsigned len;
int offset;
@@ -1502,9 +1502,9 @@
__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:
@@ -1544,7 +1544,7 @@
BR_INPUT_SKB_CB(skb)->igmp = 1;
- switch (icmp6h->icmp6_type) {
+ switch (icmp6_type) {
case ICMPV6_MGM_REPORT:
{
struct mld_msg *mld;