From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752725AbdKVCsn (ORCPT ); Tue, 21 Nov 2017 21:48:43 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:56680 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751799AbdKVCUW (ORCPT ); Tue, 21 Nov 2017 21:20:22 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Andrey Konovalov" , "Dmitry Torokhov" Date: Wed, 22 Nov 2017 01:58:13 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 124/133] Input: gtco - fix potential out-of-bound access In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.51-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Dmitry Torokhov commit a50829479f58416a013a4ccca791336af3c584c7 upstream. 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 Reviewed-by: Andrey Konovalov Signed-off-by: Dmitry Torokhov Signed-off-by: Ben Hutchings --- drivers/input/tablet/gtco.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- a/drivers/input/tablet/gtco.c +++ b/drivers/input/tablet/gtco.c @@ -231,13 +231,17 @@ static void parse_hid_report_descriptor( /* 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); + 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]; @@ -245,8 +249,7 @@ static void parse_hid_report_descriptor( case 2: data16 = get_unaligned_le16(&report[i]); break; - case 3: - size = 4; + case 4: data32 = get_unaligned_le32(&report[i]); break; }