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net/x25: Fix to not accept on connected socket

PATCH Applied Hyunwoo Kim 2 participants 3 messages Jan 23, 2023 – Jan 25, 2023

Subsystems (3)
Networking Network drivers X.25 stack

v2 of 3 Applied 1/1 Latest is v3 →

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Hyunwoo Kim

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#0 lore raw

PATCH v2 1/1 net/x25: Fix to not accept on connected socket

When listen() and accept() are called on an x25 socket that connect() succeeds, accept() succeeds immediately. This is because x25_connect() queues the skb to sk->sk_receive_queue, and x25_accept() dequeues it.

This creates a child socket with the sk of the parent x25 socket, which can cause confusion.

Fix x25_listen() to return -EINVAL if the socket has already been successfully connect()ed to avoid this issue.

Signed-off-by Hyunwoo Kim <[email protected]>
---
 net/x25/af_x25.c | 6 ++++++
 1 file changed, 6 insertions(+)
net/x25/af_x25.c +6 -0
index 3b55502b2965..5c7ad301d742 100644
@@ -482,6 +482,12 @@ static int x25_listen(struct socket *sock, int backlog)
 	int rc = -EOPNOTSUPP;
 
 	lock_sock(sk);
+	if (sock->state != SS_UNCONNECTED) {
+		rc = -EINVAL;
+		release_sock(sk);
+		return rc;
+	}
+
 	if (sk->sk_state != TCP_LISTEN) {
 		memset(&x25_sk(sk)->dest_addr, 0, X25_ADDR_LEN);
 		sk->sk_max_ack_backlog = backlog;
Signature · 1 line
2.25.1
CI Applied
#1 lore raw
This patch was applied to netdev/net.git (master) by David S. Miller <[email protected]>:

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <[email protected]>:

Quoted 9 lines · On Mon, 23 Jan 2023 11:43:23 -0800 you wrote:

When listen() and accept() are called on an x25 socket that connect() succeeds, accept() succeeds immediately. This is because x25_connect() queues the skb to sk->sk_receive_queue, and x25_accept() dequeues it.

This creates a child socket with the sk of the parent x25 socket, which can cause confusion.

[...]

Here is the summary with links:
- [v2] net/x25: Fix to not accept on connected socket

    https://git.kernel.org/netdev/net/c/f2b0b5210f67

You are awesome, thank you!

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