From: Xin Zhao <xnzhao@xxxxxxxxxx> [ Upstream commit ea427a222d8bdf2bc1a8a6da3ebe247f7dced70c ] The initial value of hid->collection[].parent_idx if 0. When Report descriptor doesn't contain "HID Collection", the value remains as 0. In the meanwhile, when the Report descriptor fullfill all following conditions, it will trigger hid_apply_multiplier function call. 1. Usage page is Generic Desktop Ctrls (0x01) 2. Usage is RESOLUTION_MULTIPLIER (0x48) 3. Contain any FEATURE items The while loop in hid_apply_multiplier will search the top-most collection by searching parent_idx == -1. Because all parent_idx is 0. The loop will run forever. There is a Report Descriptor triggerring the deadloop 0x05, 0x01, // Usage Page (Generic Desktop Ctrls) 0x09, 0x48, // Usage (0x48) 0x95, 0x01, // Report Count (1) 0x75, 0x08, // Report Size (8) 0xB1, 0x01, // Feature Signed-off-by: Xin Zhao <xnzhao@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230130212947.1315941-1-xnzhao@xxxxxxxxxx Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/hid/hid-core.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 2888bd5502f3f..0c8075d9717cb 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1190,6 +1190,7 @@ int hid_open_report(struct hid_device *device) __u8 *end; __u8 *next; int ret; + int i; static int (*dispatch_type[])(struct hid_parser *parser, struct hid_item *item) = { hid_parser_main, @@ -1240,6 +1241,8 @@ int hid_open_report(struct hid_device *device) goto err; } device->collection_size = HID_DEFAULT_NUM_COLLECTIONS; + for (i = 0; i < HID_DEFAULT_NUM_COLLECTIONS; i++) + device->collection[i].parent_idx = -1; ret = -EINVAL; while ((next = fetch_item(start, end, &item)) != NULL) { -- 2.39.0
