net: fix cipso packet validation when !NETLABEL

When CONFIG_NETLABEL is disabled, the cipso_v4_validate() function could loop
forever in the main loop if opt[opt_iter +1] == 0, this will causing a kernel
crash in an SMP system, since the CPU executing this function will
stall /not respond to IPIs.

This problem can be reproduced by running the IP Stack Integrity Checker
(http://isic.sourceforge.net) using the following command on a Linux machine
connected to DUT:

"icmpsic -s rand -d <DUT IP address> -r 123456"
wait (1-2 min)

Signed-off-by: Seif Mazareeb <seif@marvell.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 2 deletions

diff --git a/include/net/cipso_ipv4.h b/include/net/cipso_ipv4.h
index a7a683e30b64..a8c2ef6d3b93 100644
--- a/include/net/cipso_ipv4.h
+++ b/include/net/cipso_ipv4.h
@@ -290,6 +290,7 @@ static inline int cipso_v4_validate(const struct sk_buff *skb,
         unsigned char err_offset = 0;
         u8 opt_len = opt[1];
         u8 opt_iter;
+        u8 tag_len;
 
         if (opt_len < 8) {
                 err_offset = 1;
@@ -302,11 +303,12 @@ static inline int cipso_v4_validate(const struct sk_buff *skb,
         }
 
         for (opt_iter = 6; opt_iter < opt_len;) {
-                if (opt[opt_iter + 1] > (opt_len - opt_iter)) {
+                tag_len = opt[opt_iter + 1];
+                if ((tag_len == 0) || (opt[opt_iter + 1] > (opt_len - opt_iter))) {
                         err_offset = opt_iter + 1;
                         goto out;
                 }
-                opt_iter += opt[opt_iter + 1];
+                opt_iter += tag_len;
         }
 
 out: