media: v4l2-fwnode: suppress a warning at OF parsing logic

smatch produce this warning:
	drivers/media/v4l2-core/v4l2-fwnode.c:76 v4l2_fwnode_endpoint_parse_csi_bus() error: buffer overflow 'array' 5 <= u16max

That's because, in thesis, the routine might have called with
some value at bus->num_data_lanes. That's not the current
case.

Yet, better to shut up this warning, and make the code more
reliable if some future changes might cause a bug.

While here, simplify the code a little bit by reading only
once from lanes-properties array.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/drivers/media/v4l2-core/v4l2-fwnode.c b/drivers/media/v4l2-core/v4l2-fwnode.c
index ca755a4..d07c54e 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-fwnode.c
+++ b/drivers/media/v4l2-core/v4l2-fwnode.c
@@ -48,10 +48,9 @@ static int v4l2_fwnode_endpoint_parse_csi2_bus(struct fwnode_handle *fwnode,
 
        rval = fwnode_property_read_u32_array(fwnode, "data-lanes", NULL, 0);
        if (rval > 0) {
-               u32 array[ARRAY_SIZE(bus->data_lanes)];
+               u32 array[MAX_DATA_LANES + 1];
 
-               bus->num_data_lanes =
-                       min_t(int, ARRAY_SIZE(bus->data_lanes), rval);
+               bus->num_data_lanes = min_t(int, MAX_DATA_LANES, rval);
 
                fwnode_property_read_u32_array(fwnode, "data-lanes", array,
                                               bus->num_data_lanes);
@@ -64,24 +63,21 @@ static int v4l2_fwnode_endpoint_parse_csi2_bus(struct fwnode_handle *fwnode,
 
                        bus->data_lanes[i] = array[i];
                }
-       }
 
-       rval = fwnode_property_read_u32_array(fwnode, "lane-polarities", NULL,
-                                             0);
-       if (rval > 0) {
-               u32 array[ARRAY_SIZE(bus->lane_polarities)];
+               rval = fwnode_property_read_u32_array(fwnode,
+                                                     "lane-polarities", array,
+                                                     1 + bus->num_data_lanes);
+               if (rval > 0) {
+                       if (rval != 1 + bus->num_data_lanes /* clock + data */) {
+                               pr_warn("invalid number of lane-polarities entries (need %u, got %u)\n",
+                                       1 + bus->num_data_lanes, rval);
+                               return -EINVAL;
+                       }
 
-               if (rval < 1 + bus->num_data_lanes /* clock + data */) {
-                       pr_warn("too few lane-polarities entries (need %u, got %u)\n",
-                               1 + bus->num_data_lanes, rval);
-                       return -EINVAL;
-               }
 
-               fwnode_property_read_u32_array(fwnode, "lane-polarities", array,
-                                              1 + bus->num_data_lanes);
-
-               for (i = 0; i < 1 + bus->num_data_lanes; i++)
-                       bus->lane_polarities[i] = array[i];
+                       for (i = 0; i < 1 + bus->num_data_lanes; i++)
+                               bus->lane_polarities[i] = array[i];
+               }
        }
 
        if (!fwnode_property_read_u32(fwnode, "clock-lanes", &v)) {

diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
index 29ae22b..b373c43 100644 (file)
--- a/include/media/v4l2-fwnode.h
+++ b/include/media/v4l2-fwnode.h
@@ -26,6 +26,8 @@
 
 struct fwnode_handle;
 
+#define MAX_DATA_LANES 4
+
 /**
  * struct v4l2_fwnode_bus_mipi_csi2 - MIPI CSI-2 bus data structure
  * @flags: media bus (V4L2_MBUS_*) flags
@@ -37,10 +39,10 @@ struct fwnode_handle;
  */
 struct v4l2_fwnode_bus_mipi_csi2 {
        unsigned int flags;
-       unsigned char data_lanes[4];
+       unsigned char data_lanes[MAX_DATA_LANES];
        unsigned char clock_lane;
        unsigned short num_data_lanes;
-       bool lane_polarities[5];
+       bool lane_polarities[MAX_DATA_LANES + 1];
 };
 
 /**