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>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>

diff --git a/kernel/net/netfilter/ipset/ip_set_bitmap_ip.c b/kernel/net/netfilter/ipset/ip_set_bitmap_ip.c
index c488663985e53ebd847bd406fd66fce167ca41e3..f37169c7801e37906453e5d76177612e01521d8a 100644 (file)
--- a/kernel/net/netfilter/ipset/ip_set_bitmap_ip.c
+++ b/kernel/net/netfilter/ipset/ip_set_bitmap_ip.c
@@ -312,8 +312,8 @@ 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;