netfilter: ebtables: CONFIG_COMPAT: don't trust userland offsets

[mirror_ubuntu-bionic-kernel.git] / net / bridge / netfilter / ebtables.c

diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index 37817d25b63d71eaaf0ee8081d705d649c1b8d9c..895ba1cd9750214966b905264dda8c41d61329e4 100644 (file)
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -2053,7 +2053,9 @@ static int ebt_size_mwt(struct compat_ebt_entry_mwt *match32,
                if (match_kern)
                        match_kern->match_size = ret;
 
-               WARN_ON(type == EBT_COMPAT_TARGET && size_left);
+               if (WARN_ON(type == EBT_COMPAT_TARGET && size_left))
+                       return -EINVAL;
+
                match32 = (struct compat_ebt_entry_mwt *) buf;
        }
 
@@ -2109,6 +2111,15 @@ 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)
+                       return -EINVAL;
+               if (i == 0)
+                       continue;
+               if (offsets[i-1] > offsets[i])
+                       return -EINVAL;
+       }
+
        for (i = 0, j = 1 ; j < 4 ; j++, i++) {
                struct compat_ebt_entry_mwt *match32;
                unsigned int size;