From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4D220C742A2 for ; Thu, 11 Jul 2019 22:22:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 255D320872 for ; Thu, 11 Jul 2019 22:22:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="HkL0uG42" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726880AbfGKWWz (ORCPT ); Thu, 11 Jul 2019 18:22:55 -0400 Received: from mail-pg1-f202.google.com ([209.85.215.202]:49080 "EHLO mail-pg1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726207AbfGKWWz (ORCPT ); Thu, 11 Jul 2019 18:22:55 -0400 Received: by mail-pg1-f202.google.com with SMTP id k20so4419900pgg.15 for ; Thu, 11 Jul 2019 15:22:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=mCycy9aqqdoaUABFG6E8LVTO4jk0v6n9tUe0m2UvIH8=; b=HkL0uG42CEBeEhg6hS9/u6ABaO3yYAxIoLdzuP23ZxU4EmFxGd3Gu7dmmjU4FuR5X4 mPIJOhxlBiAXZYDpBlFxab4xok2wit/P5O5VdMXYUHWJ29iB1OL0LT1JLbDNF3+42Nlt kkpz+eBu8GmUjK54/LWdIdiapjPBz6bhtvdk7rXQHLtknVrVgKvSpOth4IYgk9C/koQK /bDy2iN8yGoxcb+aokz0wlTlRIS974y28FXxl3MSxvvfO6R1+HhOLGnuR2s0I/mOVFvQ jiYsMZ1qYOgihwz16+4658CM4V036Dj/nAEGU2LwNxnOjJCzQpEeybLuui0swsvyEjfo BpQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=mCycy9aqqdoaUABFG6E8LVTO4jk0v6n9tUe0m2UvIH8=; b=SkXe27KV6EqzTl7qJEmFacdwrMr7Nunv/QwlKJo+5QDyfEsNK1afqHURMU2oxU9MHE wmAYk9NM7U9pb0QkNbyqTLvFm448WdZbLr+wNW7TT85FSYCRGy6g92BMFTdl1Qgl0kp1 aitAwS0a4plOdf4NHfgEvN28U3JU/+KiLgYm5UCfBOYYIicBXz8gs/Z948vTLXQT1qS7 KHQTU6GjOpUGB19K1YagzCrQqWoHSgJxp/pJ90k7eNWD1wYElIOXUkqYQAZF6eo+zW/u NPgpsugmr6+qZKTXjKTVdsQgFZGpmTqxJlLw1C6GBckCQUJIToBKlEX3qGowcUmGBmNd mgvA== X-Gm-Message-State: APjAAAWZXgjM+rOoO/xBbMcREuxPA/YkIUCwNX4oUeiwJ/izwLBvfFMB gszAhUf9NxNhCSd5/HCziIxMK68AUXkpQCQpJXF4bw== X-Google-Smtp-Source: APXvYqy5sjDWnwnDUx+ybLSMmSX8KEPpA4NxNZqe/W7zE/QllNvWY6BNMsUoC04BN3sj4nREBDcN/q/+xxfQ+PGXHhKIHg== X-Received: by 2002:a63:1645:: with SMTP id 5mr6730418pgw.175.1562883774729; Thu, 11 Jul 2019 15:22:54 -0700 (PDT) Date: Thu, 11 Jul 2019 15:22:32 -0700 Message-Id: <20190711222232.77701-1-granthernandez@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [PATCH] Input: gtco - bounds check collection indent level From: Grant Hernandez To: dmitry.torokhov@gmail.com, linux-input@vger.kernel.org Cc: linux-usb@vger.kernel.org, Grant Hernandez , stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The GTCO tablet input driver configures itself from an HID report sent via USB during the initial enumeration process. Some debugging messages are generated during the parsing. A debugging message indentation counter is not bounds checked, leading to the ability for a specially crafted HID report to cause '-' and null bytes be written past the end of the indentation array. As long as the kernel has CONFIG_DYNAMIC_DEBUG enabled, this code will not be optimized out. This was discovered during code review after a previous syzkaller bug was found in this driver. Cc: stable@vger.kernel.org Signed-off-by: Grant Hernandez --- drivers/input/tablet/gtco.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/input/tablet/gtco.c b/drivers/input/tablet/gtco.c index 4b8b9d7aa75e..9771052ed027 100644 --- a/drivers/input/tablet/gtco.c +++ b/drivers/input/tablet/gtco.c @@ -78,6 +78,7 @@ Scott Hill shill@gtcocalcomp.com /* Max size of a single report */ #define REPORT_MAX_SIZE 10 +#define MAX_COLLECTION_LEVELS 10 /* Bitmask whether pen is in range */ @@ -223,8 +224,7 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, char maintype = 'x'; char globtype[12]; int indent = 0; - char indentstr[10] = ""; - + char indentstr[MAX_COLLECTION_LEVELS+1] = {0}; dev_dbg(ddev, "======>>>>>>PARSE<<<<<<======\n"); @@ -350,6 +350,12 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, case TAG_MAIN_COL_START: maintype = 'S'; + if (indent == MAX_COLLECTION_LEVELS) { + dev_err(ddev, "Collection level %d would exceed limit of %d\n", + indent+1, MAX_COLLECTION_LEVELS); + break; + } + if (data == 0) { dev_dbg(ddev, "======>>>>>> Physical\n"); strcpy(globtype, "Physical"); @@ -369,8 +375,15 @@ static void parse_hid_report_descriptor(struct gtco *device, char * report, break; case TAG_MAIN_COL_END: - dev_dbg(ddev, "<<<<<<======\n"); maintype = 'E'; + + if (indent == 0) { + dev_err(ddev, "Collection level already at zero\n"); + break; + } + + dev_dbg(ddev, "<<<<<<======\n"); + indent--; for (x = 0; x < indent; x++) indentstr[x] = '-'; -- 2.22.0.410.gd8fdbe21b5-goog