3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hannes Frederic Sowa <han...@stressinduktion.org>

[ Upstream commit 3a1cebe7e05027a1c96f2fc1a8eddf5f19b78f42 ]

tot_len does specify the size of struct ipv6_txoptions. We need opt_flen +
opt_nflen to calculate the overall length of additional ipv6 extensions.

I found this while auditing the ipv6 output path for a memory corruption
reported by Alexey Preobrazhensky while he fuzzed an instrumented
AddressSanitizer kernel with trinity. This may or may not be the cause
of the original bug.

Fixes: 4df98e76cde7c6 ("ipv6: pmtudisc setting not respected with UFO/CORK")
Reported-by: Alexey Preobrazhensky <pre...@google.com>
Signed-off-by: Hannes Frederic Sowa <han...@stressinduktion.org>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/ipv6/ip6_output.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1229,7 +1229,7 @@ int ip6_append_data(struct sock *sk, int
                unsigned int maxnonfragsize, headersize;
 
                headersize = sizeof(struct ipv6hdr) +
-                            (opt ? opt->tot_len : 0) +
+                            (opt ? opt->opt_flen + opt->opt_nflen : 0) +
                             (dst_allfrag(&rt->dst) ?
                              sizeof(struct frag_hdr) : 0) +
                             rt->rt6i_nfheader_len;


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