HID: hid-cypress: validate length of report

BugLink: http://bugs.launchpad.net/bugs/1656876
commit 1ebb71143758f45dc0fa76e2f48429e13b16d110 upstream.

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

Reported-by: Benoit Camredon <benoit.camredon@airbus.com>
Tested-by: Benoit Camredon <benoit.camredon@airbus.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/hid/hid-cypress.c b/drivers/hid/hid-cypress.c
index 1b764d1745f3daa693a17ee706c302ff31ae0f0e..1689568b597d4e5bb8824ccbe679f627525bf2a4 100644 (file)
--- a/drivers/hid/hid-cypress.c
+++ b/drivers/hid/hid-cypress.c
@@ -39,6 +39,9 @@ static __u8 *cp_report_fixup(struct hid_device *hdev, __u8 *rdesc,
        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;