drivers: staging: cedrus: find ctx before dereferencing it ctx

Currently if count is an invalid value the v4l2_info message will
dereference a null ctx pointer to get the dev information. Fix
this by finding ctx first and then checking for an invalid count,
this way ctxt will be non-null hence avoiding the null pointer
dereference.

Detected by CoverityScan, CID#1475337 ("Explicit null dereferenced")

Fixes: 50e761516f2b ("media: platform: Add Cedrus VPU decoder driver")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.c b/drivers/staging/media/sunxi/cedrus/cedrus.c
index 82558455384af6f1bbd576e0181261163c1bdce3..699d62dceb6cdeb4e44b9312ed2be07fc527bf21 100644 (file)
--- a/drivers/staging/media/sunxi/cedrus/cedrus.c
+++ b/drivers/staging/media/sunxi/cedrus/cedrus.c
@@ -108,17 +108,6 @@ static int cedrus_request_validate(struct media_request *req)
        unsigned int count;
        unsigned int i;
 
-       count = vb2_request_buffer_cnt(req);
-       if (!count) {
-               v4l2_info(&ctx->dev->v4l2_dev,
-                         "No buffer was provided with the request\n");
-               return -ENOENT;
-       } else if (count > 1) {
-               v4l2_info(&ctx->dev->v4l2_dev,
-                         "More than one buffer was provided with the request\n");
-               return -EINVAL;
-       }
-
        list_for_each_entry(obj, &req->objects, list) {
                struct vb2_buffer *vb;
 
@@ -133,6 +122,17 @@ static int cedrus_request_validate(struct media_request *req)
        if (!ctx)
                return -ENOENT;
 
+       count = vb2_request_buffer_cnt(req);
+       if (!count) {
+               v4l2_info(&ctx->dev->v4l2_dev,
+                         "No buffer was provided with the request\n");
+               return -ENOENT;
+       } else if (count > 1) {
+               v4l2_info(&ctx->dev->v4l2_dev,
+                         "More than one buffer was provided with the request\n");
+               return -EINVAL;
+       }
+
        parent_hdl = &ctx->hdl;
 
        hdl = v4l2_ctrl_request_hdl_find(req, parent_hdl);