| Message ID | 20230130212947.1315941-1-xnzhao@google.com |
|---|---|
| State | Accepted |
| Commit | ea427a222d8bdf2bc1a8a6da3ebe247f7dced70c |
| Headers | show |
| Series | HID: core: Fix deadloop in hid_apply_multiplier. | expand |
On Mon, 30 Jan 2023 21:29:47 +0000, Xin Zhao wrote: > 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 > > [...] Applied to hid/hid.git (for-6.2/upstream-fixes), thanks! [1/1] HID: core: Fix deadloop in hid_apply_multiplier. https://git.kernel.org/hid/hid/c/ea427a222d8b Cheers,
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 3e1803592bd4..5c72aef3d3dd 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1202,6 +1202,7 @@ 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, @@ -1252,6 +1253,8 @@ 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) {
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@google.com> --- drivers/hid/hid-core.c | 3 +++ 1 file changed, 3 insertions(+)