linux-kernel - [PATCH 5.4 080/183] net: kcm: fix incorrect parameter validation in the kcm

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Message-ID: <20240324234638.1355609-81-sashal@kernel.org>
Date: Sun, 24 Mar 2024 19:44:53 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Gavrilov Ilia <Ilia.Gavrilov@...otecs.ru>,
	"David S . Miller" <davem@...emloft.net>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.4 080/183] net: kcm: fix incorrect parameter validation in the kcm_getsockopt) function

From: Gavrilov Ilia <Ilia.Gavrilov@...otecs.ru>

[ Upstream commit 3ed5f415133f9b7518fbe55ba9ae9a3f5e700929 ]

The 'len' variable can't be negative when assigned the result of
'min_t' because all 'min_t' parameters are cast to unsigned int,
and then the minimum one is chosen.

To fix the logic, check 'len' as read from 'optlen',
where the types of relevant variables are (signed) int.

Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module")
Signed-off-by: Gavrilov Ilia <Ilia.Gavrilov@...otecs.ru>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/kcm/kcmsock.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
index 8a8ea7e6774d5..920b0ebf1cb80 100644
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1277,10 +1277,11 @@ static int kcm_getsockopt(struct socket *sock, int level, int optname,
 	if (get_user(len, optlen))
 		return -EFAULT;
 
-	len = min_t(unsigned int, len, sizeof(int));
 	if (len < 0)
 		return -EINVAL;
 
+	len = min_t(unsigned int, len, sizeof(int));
+
 	switch (optname) {
 	case KCM_RECV_DISABLE:
 		val = kcm->rx_disabled;
-- 
2.43.0