netfilter: ebtables: fix erroneous reject of last rule

commit 932909d9b28d27e807ff8eecb68c7748f6701628 upstream.

The last rule in the blob has next_entry offset that is same as total size.
This made "ebtables32 -A OUTPUT -d de:ad:be:ef:01:02" fail on 64 bit kernel.

Fixes: b71812168571fa ("netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 3a011b8..9cde6d3 100644 (file)
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2064,8 +2064,12 @@ static int size_entry_mwt(struct ebt_entry *entry, const unsigned char *base,
         * offsets are relative to beginning of struct ebt_entry (i.e., 0).
         */
        for (i = 0; i < 4 ; ++i) {
-               if (offsets[i] >= *total)
+               if (offsets[i] > *total)
                        return -EINVAL;
+
+               if (i < 3 && offsets[i] == *total)
+                       return -EINVAL;
+
                if (i == 0)
                        continue;
                if (offsets[i-1] > offsets[i])