ipv6: Disallow rediculious flowlabel option sizes.

Just like PKTINFO, limit the options area to 64K.

Based upon report by Eric Sesterhenn and analysis by
Roland Dreier.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 2 deletions

diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
index c62dd247774f..7712578bdc66 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -323,17 +323,21 @@ static struct ip6_flowlabel *
 fl_create(struct net *net, struct in6_flowlabel_req *freq, char __user *optval,
           int optlen, int *err_p)
 {
-        struct ip6_flowlabel *fl;
+        struct ip6_flowlabel *fl = NULL;
         int olen;
         int addr_type;
         int err;
 
+        olen = optlen - CMSG_ALIGN(sizeof(*freq));
+        err = -EINVAL;
+        if (olen > 64 * 1024)
+                goto done;
+
         err = -ENOMEM;
         fl = kzalloc(sizeof(*fl), GFP_KERNEL);
         if (fl == NULL)
                 goto done;
 
-        olen = optlen - CMSG_ALIGN(sizeof(*freq));
         if (olen > 0) {
                 struct msghdr msg;
                 struct flowi flowi;