[PATCH 4.4 20/27] HID: hid-cypress: validate length of report

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

commit 1ebb71143758f45dc0fa76e2f48429e13b16d110 upstream.

Make sure we have enough of a report structure to validate before
looking at it.

Reported-by: Benoit Camredon <benoit.camredon@xxxxxxxxxx>
Tested-by: Benoit Camredon <benoit.camredon@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>

---
 drivers/hid/hid-cypress.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/hid/hid-cypress.c
+++ b/drivers/hid/hid-cypress.c
@@ -39,6 +39,9 @@ static __u8 *cp_report_fixup(struct hid_
 	if (!(quirks & CP_RDESC_SWAPPED_MIN_MAX))
 		return rdesc;
 
+	if (*rsize < 4)
+		return rdesc;
+
 	for (i = 0; i < *rsize - 4; i++)
 		if (rdesc[i] == 0x29 && rdesc[i + 2] == 0x19) {
 			rdesc[i] = 0x19;