1 files changed, 37 insertions, 3 deletions

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 3942ee61bd1c..3da354af7a0a 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -128,9 +128,19 @@ static int open_collection(struct hid_parser *parser, unsigned type)
 
 	usage = parser->local.usage[0];
 
-	if (parser->collection_stack_ptr == HID_COLLECTION_STACK_SIZE) {
-		hid_err(parser->device, "collection stack overflow\n");
-		return -EINVAL;
+	if (parser->collection_stack_ptr == parser->collection_stack_size) {
+		unsigned int *collection_stack;
+		unsigned int new_size = parser->collection_stack_size +
+					HID_COLLECTION_STACK_SIZE;
+
+		collection_stack = krealloc(parser->collection_stack,
+					    new_size * sizeof(unsigned int),
+					    GFP_KERNEL);
+		if (!collection_stack)
+			return -ENOMEM;
+
+		parser->collection_stack = collection_stack;
+		parser->collection_stack_size = new_size;
 	}
 
 	if (parser->device->maxcollection == parser->device->collection_size) {
@@ -840,6 +850,7 @@ static int hid_scan_report(struct hid_device *hid)
 		break;
 	}
 
+	kfree(parser->collection_stack);
 	vfree(parser);
 	return 0;
 }
@@ -1939,6 +1950,29 @@ static int hid_bus_match(struct device *dev, struct device_driver *drv)
 	return hid_match_device(hdev, hdrv) != NULL;
 }
 
+/**
+ * hid_compare_device_paths - check if both devices share the same path
+ * @hdev_a: hid device
+ * @hdev_b: hid device
+ * @separator: char to use as separator
+ *
+ * Check if two devices share the same path up to the last occurrence of
+ * the separator char. Both paths must exist (i.e., zero-length paths
+ * don't match).
+ */
+bool hid_compare_device_paths(struct hid_device *hdev_a,
+			      struct hid_device *hdev_b, char separator)
+{
+	int n1 = strrchr(hdev_a->phys, separator) - hdev_a->phys;
+	int n2 = strrchr(hdev_b->phys, separator) - hdev_b->phys;
+
+	if (n1 != n2 || n1 <= 0 || n2 <= 0)
+		return false;
+
+	return !strncmp(hdev_a->phys, hdev_b->phys, n1);
+}
+EXPORT_SYMBOL_GPL(hid_compare_device_paths);
+
 static int hid_device_probe(struct device *dev)
 {
 	struct hid_driver *hdrv = to_hid_driver(dev->driver);