xen/pvcalls-back: fix double frees with pvcalls_new_active_socket()

commit 8fafac202d18230bb9926bda48e563fd2cce2a4f upstream.

In the pvcalls_new_active_socket() function, most error paths call
pvcalls_back_release_active(fedata->dev, fedata, map) which calls
sock_release() on "sock".  The bug is that the caller also frees sock.

Fix this by making every error path in pvcalls_new_active_socket()
release the sock, and don't free it in the caller.

Fixes: 5db4d286a8ef ("xen/pvcalls: implement connect command")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/e5f98dc2-0305-491f-a860-71bbd1398a2f@kili.mountain
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index 9c267e27d9d95a18f8f6d5a471438ebc1bdd1719..6c2afd8bbf52249e753d7a18a6383771a93b319f 100644 (file)
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -321,8 +321,10 @@ static struct sock_mapping *pvcalls_new_active_socket(
        void *page;
 
        map = kzalloc(sizeof(*map), GFP_KERNEL);
-       if (map == NULL)
+       if (map == NULL) {
+               sock_release(sock);
                return NULL;
+       }
 
        map->fedata = fedata;
        map->sock = sock;
@@ -414,10 +416,8 @@ static int pvcalls_back_connect(struct xenbus_device *dev,
                                        req->u.connect.ref,
                                        req->u.connect.evtchn,
                                        sock);
-       if (!map) {
+       if (!map)
                ret = -EFAULT;
-               sock_release(sock);
-       }
 
 out:
        rsp = RING_GET_RESPONSE(&fedata->ring, fedata->ring.rsp_prod_pvt++);
@@ -558,7 +558,6 @@ static void __pvcalls_back_accept(struct work_struct *work)
                                        sock);
        if (!map) {
                ret = -EFAULT;
-               sock_release(sock);
                goto out_error;
        }