[PATCH 10/10] HID: zydacron: validate key report length

The HID core invokes raw_event callbacks before validating the report
length.  zc_raw_event() verifies the report ID in byte zero and then reads
the key code from byte one for report IDs 0x02 and 0x03 without checking
that the second byte is present.

A one-byte report reproduced the issue under KASAN:

  BUG: KASAN: slab-out-of-bounds in zc_raw_event+0x54c/0x580
  Read of size 1 by task hidtrigger/93
  Call Trace:
   zc_raw_event+0x54c/0x580
   __hid_input_report+0x2ef/0x3a0
   inject_store+0x479/0x490 [faketrans]

Require both the report ID and key code before processing the report.

Commit 47669bec44fe ("HID: asus: refactor the two workqueues and init
sequence") added the same kind of raw_event length validation to hid-asus.

Fixes: d0742abaa1c3 ("HID: add omitted hid-zydacron.c file")
Cc: stable@vger.kernel.org
Signed-off-by: Jiale Yao <redacted>
---
 drivers/hid/hid-zydacron.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hid/hid-zydacron.c b/drivers/hid/hid-zydacron.c
index 1aae80f848f5..02de153d5628 100644
--- a/drivers/hid/hid-zydacron.c
+++ b/drivers/hid/hid-zydacron.c

@@ -114,6 +114,9 @@ static int zc_raw_event(struct hid_device *hdev, struct hid_report *report,
 	unsigned key;
 	unsigned short index;
 
+	if (size < 2)
+		return 0;
+
 	if (report->id == data[0] && (hdev->claimed & HID_CLAIMED_INPUT)) {
 
 		/* break keys */

-- 
2.34.1