HID: hid-cypress: validate length of report

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

Orabug: 25795985
CVE: CVE-2017-7273

Reported-by: Benoit Camredon <benoit.camredon@airbus.com>
Tested-by: Benoit Camredon <benoit.camredon@airbus.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
(cherry picked from commit 1ebb71143758f45dc0fa76e2f48429e13b16d110)
Signed-off-by: Aniket Alshi <aniket.alshi@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>

diff --git a/drivers/hid/hid-cypress.c b/drivers/hid/hid-cypress.c
index c4ef3bc726e34e5e08aa947b64ddfa4dc7f772b0..e299576004ce52c6d9042a2caf223279ecc095a9 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) {
                        __u8 tmp;