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>

diff --git a/include/net/cipso_ipv4.h b/include/net/cipso_ipv4.h
index a7a683e..a8c2ef6 100644 (file)
--- 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: