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From:   Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
To:     Pablo Neira Ayuso <pablo@netfilter.org>
CC:     Jozsef Kadlecsik <kadlec@netfilter.org>,
        Florian Westphal <fw@strlen.de>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        "netfilter-devel@vger.kernel.org" <netfilter-devel@vger.kernel.org>,
        "coreteam@netfilter.org" <coreteam@netfilter.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "lvc-project@linuxtesting.org" <lvc-project@linuxtesting.org>
Subject: [PATCH] netfilter: ipset: Fix overflow before widen in the
 bitmap_ip_create() function.
Thread-Topic: [PATCH] netfilter: ipset: Fix overflow before widen in the
 bitmap_ip_create() function.
Thread-Index: AQHZJCER6ItbAfvk9EO+bS1fujtoFQ==
Date:   Mon, 9 Jan 2023 11:54:02 +0000
Message-ID: <20230109115432.3001636-1-Ilia.Gavrilov@infotecs.ru>
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When first_ip is 0, last_ip is 0xFFFFFFF, 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 par=
ameters")
Signed-off-by: Ilia.Gavrilov <Ilia.Gavrilov@infotecs.ru>
---
 net/netfilter/ipset/ip_set_bitmap_ip.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/ipset/ip_set_bitmap_ip.c b/net/netfilter/ipset/i=
p_set_bitmap_ip.c
index a8ce04a4bb72..b8f0fb37378f 100644
--- a/net/netfilter/ipset/ip_set_bitmap_ip.c
+++ b/net/netfilter/ipset/ip_set_bitmap_ip.c
@@ -309,7 +309,7 @@ bitmap_ip_create(struct net *net, struct ip_set *set, s=
truct nlattr *tb[],
=20
 		pr_debug("mask_bits %u, netmask %u\n", mask_bits, netmask);
 		hosts =3D 2 << (32 - netmask - 1);
-		elements =3D 2 << (netmask - mask_bits - 1);
+		elements =3D 2UL << (netmask - mask_bits - 1);
 	}
 	if (elements > IPSET_BITMAP_MAX_RANGE + 1)
 		return -IPSET_ERR_BITMAP_RANGE_SIZE;
--=20
2.30.2