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

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

commit 9ea4b476cea1b7d461d16dda25ca3c7e616e2d15 upstream.

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")
Change-Id: I13e759e84d67e14d3d34aa63e8e22299a6a18a34
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit e137d9bb26bd85ce07323a38e38ceb0b160db841)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>