[PATCH 4.12 66/99] RDMA/uverbs: Initialize cq_context appropriately

[Greg Kroah-Hartman]

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

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

From: Bharat Potnuri <bharat@xxxxxxxxxxx>

commit 65159c051c45f269cf40a14f9404248f2d524920 upstream.

Initializing cq_context with ev_queue in create_cq(), leads to NULL pointer
dereference in ib_uverbs_comp_handler(), if application doesnot use completion
channel. This patch fixes the cq_context initialization.

Fixes: 1e7710f3f65 ("IB/core: Change completion channel to use the reworked")
Signed-off-by: Potnuri Bharat Teja <bharat@xxxxxxxxxxx>
Reviewed-by: Matan Barak <matanb@xxxxxxxxxxxx>
Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx>
(cherry picked from commit 699a2d5b1b880b4e4e1c7d55fa25659322cf5b51)
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/infiniband/core/uverbs_cmd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/infiniband/core/uverbs_cmd.c
+++ b/drivers/infiniband/core/uverbs_cmd.c
@@ -1015,7 +1015,7 @@ static struct ib_ucq_object *create_cq(s
 	cq->uobject       = &obj->uobject;
 	cq->comp_handler  = ib_uverbs_comp_handler;
 	cq->event_handler = ib_uverbs_cq_event_handler;
-	cq->cq_context    = &ev_file->ev_queue;
+	cq->cq_context    = ev_file ? &ev_file->ev_queue : NULL;
 	atomic_set(&cq->usecnt, 0);
 
 	obj->uobject.object = cq;