linux-kernel - [PATCH] net/socket: clamp negative backlog value to 0 in listen()

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Message-Id: <20240628172836.19213-1-cosiekvfj@o2.pl>
Date: Fri, 28 Jun 2024 19:28:36 +0200
From: Kacper Piwiński <cosiekvfj@...pl>
To: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Kacper Piwiński <cosiekvfj@...pl>
Subject: [PATCH] net/socket: clamp negative backlog value to 0 in listen()

According to manual: https://man7.org/linux/man-pages/man3/listen.3p.html
If listen() is called with a backlog argument value that is less
than 0, the function behaves as if it had been called with a
backlog argument value of 0.

Signed-off-by: Kacper Piwiński <cosiekvfj@...pl>
---
 net/socket.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/net/socket.c b/net/socket.c
index e416920e9..9567223d7 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1873,8 +1873,7 @@ int __sys_listen(int fd, int backlog)
 	sock = sockfd_lookup_light(fd, &err, &fput_needed);
 	if (sock) {
 		somaxconn = READ_ONCE(sock_net(sock->sk)->core.sysctl_somaxconn);
-		if ((unsigned int)backlog > somaxconn)
-			backlog = somaxconn;
+		backlog = clamp(backlog, 0, somaxconn);
 
 		err = security_socket_listen(sock, backlog);
 		if (!err)
-- 
2.34.1