Commit 0908cf4d authored May 25, 2017 by linzhang Committed by David S. Miller May 26, 2017

net: llc: add lock_sock in llc_ui_bind to avoid a race condition



There is a race condition in llc_ui_bind if two or more processes/threads
try to bind a same socket.

If more processes/threads bind a same socket success that will lead to
two problems, one is this action is not what we expected, another is
will lead to kernel in unstable status or oops(in my simple test case,
cause llc2.ko can't unload).

The current code is test SOCK_ZAPPED bit to avoid a process to
bind a same socket twice but that is can't avoid more processes/threads
try to bind a same socket at the same time.

So, add lock_sock in llc_ui_bind like others, such as llc_ui_connect.

Signed-off-by: Lin Zhang <xiaolou4617@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 797a9364

net/llc/af_llc.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -311,6 +311,8 @@ static int llc_ui_bind(struct socket sock, struct sockaddr uaddr, int addrlen)
		int rc = -EINVAL;

		dprintk("%s: binding %02X\n", __func__, addr->sllc_sap);

		lock_sock(sk);
		if (unlikely(!sock_flag(sk, SOCK_ZAPPED) \|\| addrlen != sizeof(*addr)))
		goto out;
		rc = -EAFNOSUPPORT;
		@@ -382,6 +384,7 @@ static int llc_ui_bind(struct socket sock, struct sockaddr uaddr, int addrlen)
		out_put:
		llc_sap_put(sap);
		out:
		release_sock(sk);
		return rc;
		}

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