[PATCH 4.20 022/183] pvcalls-front: dont try to free unallocated rings

[Greg Kroah-Hartman]

4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 96283f9a084e23d7cda2d3c5d1ffa6df6cf1ecec ]

inflight_req_id is 0 when initialized. If inflight_req_id is 0, there is
no accept_map to free. Fix the check in pvcalls_front_release.

Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/xen/pvcalls-front.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/pvcalls-front.c b/drivers/xen/pvcalls-front.c
index e5d95aab2cb80..4f3d664b3f39e 100644
--- a/drivers/xen/pvcalls-front.c
+++ b/drivers/xen/pvcalls-front.c
@@ -1030,8 +1030,8 @@ int pvcalls_front_release(struct socket *sock)
 		spin_lock(&bedata->socket_lock);
 		list_del(&map->list);
 		spin_unlock(&bedata->socket_lock);
-		if (READ_ONCE(map->passive.inflight_req_id) !=
-		    PVCALLS_INVALID_ID) {
+		if (READ_ONCE(map->passive.inflight_req_id) != PVCALLS_INVALID_ID &&
+			READ_ONCE(map->passive.inflight_req_id) != 0) {
 			pvcalls_front_free_map(bedata,
 					       map->passive.accept_map);
 		}
-- 
2.19.1