[PATCH 6/7] RDMA/siw: Fix new_cep use-after-free in siw_accept_newconn()

[Wentao Liang <vulab@iscas.ac.cn>]

On the error path the listening endpoint reference of new_cep is
dropped before the accepted socket is disassociated.  When only the
socket's reference remains, siw_socket_disassoc() drops that last
reference and frees the endpoint, leaving the subsequent
'new_cep->sock = NULL' writing into freed memory.

Tear the accepted socket down first and put the endpoint last.

Fixes: 6c52fdc244b5 ("rdma/siw: connection management")
Cc: stable@vger.kernel.org
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/infiniband/sw/siw/siw_cm.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_cm.c b/drivers/infiniband/sw/siw/siw_cm.c
index f7ac81c0f267..1b93963cb191 100644
--- a/drivers/infiniband/sw/siw/siw_cm.c
+++ b/drivers/infiniband/sw/siw/siw_cm.c
@@ -1044,14 +1044,16 @@ static void siw_accept_newconn(struct siw_cep *cep)
 	return;
 
 error:
-	if (new_cep)
-		siw_cep_put(new_cep);
-
 	if (new_s) {
 		siw_socket_disassoc(new_s);
 		sock_release(new_s);
-		new_cep->sock = NULL;
+		if (new_cep)
+			new_cep->sock = NULL;
 	}
+
+	if (new_cep)
+		siw_cep_put(new_cep);
+
 	siw_dbg_cep(cep, "error %d\n", rv);
 }
 
-- 
2.34.1