netfilter: conntrack: avoid integer overflow when resizing

Can overflow so we might allocate very small table when bucket count is
high on a 32bit platform.

Note: resize is only possible from init_netns.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index f204274a9b6b9dfaa0bc66d69c15d85255a87a17..62c42e970c893488ff693f2d828bb6ae115d1cc1 100644 (file)
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1601,8 +1601,15 @@ void *nf_ct_alloc_hashtable(unsigned int *sizep, int nulls)
        unsigned int nr_slots, i;
        size_t sz;
 
+       if (*sizep > (UINT_MAX / sizeof(struct hlist_nulls_head)))
+               return NULL;
+
        BUILD_BUG_ON(sizeof(struct hlist_nulls_head) != sizeof(struct hlist_head));
        nr_slots = *sizep = roundup(*sizep, PAGE_SIZE / sizeof(struct hlist_nulls_head));
+
+       if (nr_slots > (UINT_MAX / sizeof(struct hlist_nulls_head)))
+               return NULL;
+
        sz = nr_slots * sizeof(struct hlist_nulls_head);
        hash = (void *)__get_free_pages(GFP_KERNEL | __GFP_NOWARN | __GFP_ZERO,
                                        get_order(sz));