3.18-stable review patch. If anyone has any objections, please let me know.
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From: linzhang xiaolou4617@gmail.com
[ Upstream commit 0908cf4dfef35fc6ac12329007052ebe93ff1081 ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/llc/af_llc.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/llc/af_llc.c +++ b/net/llc/af_llc.c @@ -309,6 +309,8 @@ static int llc_ui_bind(struct socket *so 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; @@ -380,6 +382,7 @@ static int llc_ui_bind(struct socket *so out_put: llc_sap_put(sap); out: + release_sock(sk); return rc; }