netdev - [PATCH] bridge: fix a possible use after free

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 24 Aug 2011 07:57:05 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org, Herbert Xu <herbert@...dor.apana.org.au>,
	Stephen Hemminger <shemminger@...tta.com>
Subject: [PATCH] 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@...il.com>
---
 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;


--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html