netfilter: ipset: Fix overflow before widen in the bitmap_ip_create() function.

When first_ip is 0, last_ip is 0xFFFFFFFF, and netmask is 31, the value of
an arithmetic expression 2 << (netmask - mask_bits - 1) is subject
to overflow due to a failure casting operands to a larger data type
before performing the arithmetic.

Note that it's harmless since the value will be checked at the next step.

Found by InfoTeCS on behalf of Linux Verification Center
(linuxtesting.org) with SVACE.

Fixes: b9fed748185a ("netfilter: ipset: Check and reject crazy /0 input parameters")
Signed-off-by: Ilia.Gavrilov <Ilia.Gavrilov@infotecs.ru>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/ipset/ip_set_bitmap_ip.c b/net/netfilter/ipset/ip_set_bitmap_ip.c
index a8ce04a4bb72abef52524edad94dc7d69d39458a..e4fa00abde6a2ab9941c8cd7d0b8a12f537503e0 100644 (file)
--- a/net/netfilter/ipset/ip_set_bitmap_ip.c
+++ b/net/netfilter/ipset/ip_set_bitmap_ip.c
@@ -308,8 +308,8 @@ bitmap_ip_create(struct net *net, struct ip_set *set, struct nlattr *tb[],
                        return -IPSET_ERR_BITMAP_RANGE;
 
                pr_debug("mask_bits %u, netmask %u\n", mask_bits, netmask);
-               hosts = 2 << (32 - netmask - 1);
-               elements = 2 << (netmask - mask_bits - 1);
+               hosts = 2U << (32 - netmask - 1);
+               elements = 2UL << (netmask - mask_bits - 1);
        }
        if (elements > IPSET_BITMAP_MAX_RANGE + 1)
                return -IPSET_ERR_BITMAP_RANGE_SIZE;