From patchwork Mon Mar 1 16:13:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 389999 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=-23.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=ham 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 C09E5C433DB for ; Mon, 1 Mar 2021 17:24:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 966DB64F96 for ; Mon, 1 Mar 2021 17:24:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237921AbhCARWN (ORCPT ); Mon, 1 Mar 2021 12:22:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:52684 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237864AbhCARNj (ORCPT ); Mon, 1 Mar 2021 12:13:39 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0D34564E54; Mon, 1 Mar 2021 16:43:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614617040; bh=aLK6ffcBiRedT1F3NNJKUOGr5BbyA71bN8TWbZPxhCg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=R3BOZ/o2cve0PWfOLui5BV6aZ1J3Fa/kF3OOQU8kmopDBeTXIuYQVu0VxFjBPMOkB cEv+XzGfcux5ryuj+aIuqHrfR7wpii/alyr2crZWhL2hPn93HB3lrlGFfcNMn+pV3R RnM6tFRLFVsY0HaEfvJtabdP7gEYaxOSgIfdxFo8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jason Gerecke , Jiri Kosina Subject: [PATCH 4.19 181/247] HID: wacom: Ignore attempts to overwrite the touch_max value from HID Date: Mon, 1 Mar 2021 17:13:21 +0100 Message-Id: <20210301161040.520537632@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210301161031.684018251@linuxfoundation.org> References: <20210301161031.684018251@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jason Gerecke commit 88f38846bfb1a452a3d47e38aeab20a4ceb74294 upstream. The `wacom_feature_mapping` function is careful to only set the the touch_max value a single time, but this care does not extend to the `wacom_wac_finger_event` function. In particular, if a device sends multiple HID_DG_CONTACTMAX items in a single feature report, the driver will end up retaining the value of last item. The HID descriptor for the Cintiq Companion 2 does exactly this. It incorrectly sets a "Report Count" of 2, which will cause the driver to process two HID_DG_CONTACTCOUNT items. The first item has the actual count, while the second item should have been declared as a constant zero. The constant zero is the value the driver ends up using, however, since it is the last HID_DG_CONTACTCOUNT in the report. Report ID (16), Usage (Contact Count Maximum), ; Contact count maximum (55h, static value) Report Count (2), Logical Maximum (10), Feature (Variable), To address this, we add a check that the touch_max is not already set within the `wacom_wac_finger_event` function that processes the HID_DG_TOUCHMAX item. We emit a warning if the value is set and ignore the updated value. This could potentially cause problems if there is a tablet which has a similar issue but requires the last item to be used. This is unlikely, however, since it would have to have a different non-zero value for HID_DG_CONTACTMAX earlier in the same report, which makes no sense except in the case of a firmware bug. Note that cases where the HID_DG_CONTACTMAX items are in different reports is already handled (and similarly ignored) by `wacom_feature_mapping` as mentioned above. Link: https://github.com/linuxwacom/input-wacom/issues/223 Fixes: 184eccd40389 ("HID: wacom: generic: read HID_DG_CONTACTMAX from any feature report") Signed-off-by: Jason Gerecke CC: stable@vger.kernel.org Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- drivers/hid/wacom_wac.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/hid/wacom_wac.c +++ b/drivers/hid/wacom_wac.c @@ -2557,7 +2557,12 @@ static void wacom_wac_finger_event(struc wacom_wac->hid_data.tipswitch = value; break; case HID_DG_CONTACTMAX: - features->touch_max = value; + if (!features->touch_max) { + features->touch_max = value; + } else { + hid_warn(hdev, "%s: ignoring attempt to overwrite non-zero touch_max " + "%d -> %d\n", __func__, features->touch_max, value); + } return; }