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From: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>, David Ahern <dsahern@kernel.org>,
	Eric Dumazet <edumazet@google.com>, Jakub Kicinski <kuba@kernel.org>, "Paolo
 Abeni" <pabeni@redhat.com>, "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 net-next] udp: fix incorrect parameter validation in the
 udp_lib_getsockopt() function
Thread-Topic: [PATCH net-next] udp: fix incorrect parameter validation in the
 udp_lib_getsockopt() function
Thread-Index: AQHab6zDS4CyiiE6UEiU3tkyNekepQ==
Date: Wed, 6 Mar 2024 09:57:57 +0000
Message-ID: <20240306095436.1782250-1-Ilia.Gavrilov@infotecs.ru>
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The 'len' variable can't be negative because all 'min_t' parameters
cast to unsigned int, and then the minimum one is chosen.

To fix it, move the if statement higher.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
---
 net/ipv4/udp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index e474b201900f..17231c0f8830 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2792,11 +2792,11 @@ int udp_lib_getsockopt(struct sock *sk, int level, =
int optname,
 	if (get_user(len, optlen))
 		return -EFAULT;
=20
-	len =3D min_t(unsigned int, len, sizeof(int));
-
 	if (len < 0)
 		return -EINVAL;
=20
+	len =3D min_t(unsigned int, len, sizeof(int));
+
 	switch (optname) {
 	case UDP_CORK:
 		val =3D udp_test_bit(CORK, sk);
--=20
2.39.2