[IPV6]: Fix kernel OOPs when setting sticky socket options.

Bug noticed by Remi Denis-Courmont <rdenis@simphalempin.com>.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 16 insertions, 13 deletions

diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 9d0ee7f0eeb..86dac106873 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -635,14 +635,17 @@ ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
         struct ipv6_txoptions *opt2;
         int err;
 
-        if (newtype != IPV6_HOPOPTS && opt->hopopt)
-                tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
-        if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
-                tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
-        if (newtype != IPV6_RTHDR && opt->srcrt)
-                tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
-        if (newtype != IPV6_DSTOPTS && opt->dst1opt)
-                tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
+        if (opt) {
+                if (newtype != IPV6_HOPOPTS && opt->hopopt)
+                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->hopopt));
+                if (newtype != IPV6_RTHDRDSTOPTS && opt->dst0opt)
+                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst0opt));
+                if (newtype != IPV6_RTHDR && opt->srcrt)
+                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->srcrt));
+                if (newtype != IPV6_DSTOPTS && opt->dst1opt)
+                        tot_len += CMSG_ALIGN(ipv6_optlen(opt->dst1opt));
+        }
+
         if (newopt && newoptlen)
                 tot_len += CMSG_ALIGN(newoptlen);
 
@@ -659,25 +662,25 @@ ipv6_renew_options(struct sock *sk, struct ipv6_txoptions *opt,
         opt2->tot_len = tot_len;
         p = (char *)(opt2 + 1);
 
-        err = ipv6_renew_option(opt->hopopt, newopt, newoptlen,
+        err = ipv6_renew_option(opt ? opt->hopopt : NULL, newopt, newoptlen,
                                 newtype != IPV6_HOPOPTS,
                                 &opt2->hopopt, &p);
         if (err)
                 goto out;
 
-        err = ipv6_renew_option(opt->dst0opt, newopt, newoptlen,
+        err = ipv6_renew_option(opt ? opt->dst0opt : NULL, newopt, newoptlen,
                                 newtype != IPV6_RTHDRDSTOPTS,
                                 &opt2->dst0opt, &p);
         if (err)
                 goto out;
 
-        err = ipv6_renew_option(opt->srcrt, newopt, newoptlen,
+        err = ipv6_renew_option(opt ? opt->srcrt : NULL, newopt, newoptlen,
                                 newtype != IPV6_RTHDR,
-                                (struct ipv6_opt_hdr **)opt2->srcrt, &p);
+                                (struct ipv6_opt_hdr **)&opt2->srcrt, &p);
         if (err)
                 goto out;
 
-        err = ipv6_renew_option(opt->dst1opt, newopt, newoptlen,
+        err = ipv6_renew_option(opt ? opt->dst1opt : NULL, newopt, newoptlen,
                                 newtype != IPV6_DSTOPTS,
                                 &opt2->dst1opt, &p);
         if (err)