Cipso: cipso_v4_optptr enter infinite loop

Orabug: 28563992
CVE: CVE-2018-10938

in for(),if((optlen > 0) && (optptr[1] == 0)), enter infinite loop.

Test: receive a packet which the ip length > 20 and the first byte of ip option is 0, produce this issue

Signed-off-by: yujuan.qi <yujuan.qi@mediatek.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 40413955ee265a5e42f710940ec78f5450d49149)
Signed-off-by: Somasundaram Krishnasamy <somasundaram.krishnasamy@oracle.com>
Reviewed-by: Brian Maly <brian.maly@oracle.com
Signed-off-by: Brian Maly <brian.maly@oracle.com>

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index bdb2a07ec363b709197435ac602b74377a600780..b77502018e26079e5e09fd014958878335d79e3d 100644 (file)
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1593,9 +1593,17 @@ unsigned char *cipso_v4_optptr(const struct sk_buff *skb)
        int taglen;
 
        for (optlen = iph->ihl*4 - sizeof(struct iphdr); optlen > 0; ) {
-               if (optptr[0] == IPOPT_CIPSO)
+               switch (optptr[0]) {
+               case IPOPT_CIPSO:
                        return optptr;
-               taglen = optptr[1];
+               case IPOPT_END:
+                       return NULL;
+               case IPOPT_NOOP:
+                       taglen = 1;
+                       break;
+               default:
+                       taglen = optptr[1];
+               }
                optlen -= taglen;
                optptr += taglen;
        }