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From: Gavrilov Ilia <Ilia.Gavrilov@infotecs.ru>
To: Eric Dumazet <edumazet@google.com>
CC: "David S. Miller" <davem@davemloft.net>, David Ahern <dsahern@kernel.org>,
	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] tcp: fix incorrect parameter validation in the
 do_tcp_getsockopt() function
Thread-Topic: [PATCH net-next] tcp: fix incorrect parameter validation in the
 do_tcp_getsockopt() function
Thread-Index: AQHab6y/ymlnx20eHUyJFqMhxuWaSg==
Date: Wed, 6 Mar 2024 09:57:50 +0000
Message-ID: <20240306095430.1782163-1-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/tcp.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index c82dc42f57c6..a4f418592314 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -4010,11 +4010,11 @@ int do_tcp_getsockopt(struct sock *sk, int level,
 	if (copy_from_sockptr(&len, optlen, sizeof(int)))
 		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 TCP_MAXSEG:
 		val =3D tp->mss_cache;
--=20
2.39.2