netfilter: ipset: fixes possible oops in mtype_resize

currently mtype_resize() can cause oops

        t = ip_set_alloc(htable_size(htable_bits));
        if (!t) {
                ret = -ENOMEM;
                goto out;
        }
        t->hregion = ip_set_alloc(ahash_sizeof_regions(htable_bits));

Increased htable_bits can force htable_size() to return 0.
In own turn ip_set_alloc(0) returns not 0 but ZERO_SIZE_PTR,
so follwoing access to t->hregion should trigger an OOPS.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Jozsef Kadlecsik <kadlec@netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/ipset/ip_set_hash_gen.h b/net/netfilter/ipset/ip_set_hash_gen.h
index 5f1208a..1e7dddf 100644 (file)
--- a/net/netfilter/ipset/ip_set_hash_gen.h
+++ b/net/netfilter/ipset/ip_set_hash_gen.h
@@ -640,7 +640,7 @@ mtype_resize(struct ip_set *set, bool retried)
        struct htype *h = set->data;
        struct htable *t, *orig;
        u8 htable_bits;
-       size_t dsize = set->dsize;
+       size_t hsize, dsize = set->dsize;
 #ifdef IP_SET_HASH_WITH_NETS
        u8 flags;
        struct mtype_elem *tmp;
@@ -664,14 +664,12 @@ mtype_resize(struct ip_set *set, bool retried)
 retry:
        ret = 0;
        htable_bits++;
-       if (!htable_bits) {
-               /* In case we have plenty of memory :-) */
-               pr_warn("Cannot increase the hashsize of set %s further\n",
-                       set->name);
-               ret = -IPSET_ERR_HASH_FULL;
-               goto out;
-       }
-       t = ip_set_alloc(htable_size(htable_bits));
+       if (!htable_bits)
+               goto hbwarn;
+       hsize = htable_size(htable_bits);
+       if (!hsize)
+               goto hbwarn;
+       t = ip_set_alloc(hsize);
        if (!t) {
                ret = -ENOMEM;
                goto out;
@@ -813,6 +811,12 @@ cleanup:
        if (ret == -EAGAIN)
                goto retry;
        goto out;
+
+hbwarn:
+       /* In case we have plenty of memory :-) */
+       pr_warn("Cannot increase the hashsize of set %s further\n", set->name);
+       ret = -IPSET_ERR_HASH_FULL;
+       goto out;
 }
 
 /* Get the current number of elements and ext_size in the set  */