HID: core: do not upper bound the collection stack

Looks like 4 was sufficient until now. However, the Surface Dial needs
a stack of 5 and simply fails at probing.
Dynamically add HID_COLLECTION_STACK_SIZE to the size of the stack if
we hit the upper bound.

Checkpatch complains about bare unsigned, so converting those to
'unsigned int' in struct hid_parser

Acked-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 14 insertions, 3 deletions

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 3942ee61bd1c..5de6f18c9bf7 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;
 }