From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: [PATCH] Input: gtco - fix potential out-of-bound access Date: Mon, 23 Oct 2017 22:28:23 -0700 Message-ID: <20171024052823.jpetpk2bfazfvfah@dtor-ws> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-io0-f196.google.com ([209.85.223.196]:45657 "EHLO mail-io0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751399AbdJXF21 (ORCPT ); Tue, 24 Oct 2017 01:28:27 -0400 Content-Disposition: inline Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: linux-input@vger.kernel.org Cc: Andrey Konovalov , linux-kernel@vger.kernel.org parse_hid_report_descriptor() has a while (i < length) loop, which only guarantees that there's at least 1 byte in the buffer, but the loop body can read multiple bytes which causes out-of-bounds access. Reported-by: Andrey Konovalov Signed-off-by: Dmitry Torokhov --- drivers/input/tablet/gtco.c | 24 +++++++++++++++++------- 1 file changed, 17 insertions(+), 7 deletions(-) diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c index b796e891e2ee..0351203b8c24 100644 --- a/drivers/input/tablet/gtco.c +++ b/drivers/input/tablet/gtco.c @@ -230,13 +230,24 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, /* Walk this report and pull out the info we need */ while (i < length) { - prefix = report[i]; - - /* Skip over prefix */ - i++; + prefix = report[i++]; /* Determine data size and save the data in the proper variable */ - size = PREF_SIZE(prefix); + if (PREF_SIZE(prefix) < 1) { + dev_err(ddev, + "Invalid size %d in element at offset %d\n", + PREF_SIZE(prefix), i); + break; + } + + size = 1U << (PREF_SIZE(prefix) - 1); + if (i + size >= length) { + dev_err(ddev, + "Not enough data (need %d, have %d)\n", + i + size, length); + break; + } + switch (size) { case 1: data = report[i]; @@ -244,8 +255,7 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, case 2: data16 = get_unaligned_le16(&report[i]); break; - case 3: - size = 4; + case 4: data32 = get_unaligned_le32(&report[i]); break; } -- 2.15.0.rc0.271.g36b669edcc-goog -- Dmitry