From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754186AbbLXVUY (ORCPT ); Thu, 24 Dec 2015 16:20:24 -0500 Received: from mail-wm0-f53.google.com ([74.125.82.53]:37124 "EHLO mail-wm0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753343AbbLXVTG (ORCPT ); Thu, 24 Dec 2015 16:19:06 -0500 From: =?UTF-8?q?Pali=20Roh=C3=A1r?= To: Matthew Garrett , Darren Hart , Gabriele Mazzotta , =?UTF-8?q?Micha=C5=82=20K=C4=99pie=C5=84?= Cc: Andy Lutomirski , platform-driver-x86@vger.kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?q?Pali=20Roh=C3=A1r?= Subject: [PATCH 2/2] dell-wmi: Process only one event on devices with interface version 0 Date: Thu, 24 Dec 2015 22:18:46 +0100 Message-Id: <1450991926-20937-3-git-send-email-pali.rohar@gmail.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1450991926-20937-1-git-send-email-pali.rohar@gmail.com> References: <1450991926-20937-1-git-send-email-pali.rohar@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org BIOS/ACPI on devices with WMI interface version 0 does not clear buffer before filling it. So next time when BIOS/ACPI send WMI event which is smaller as previous then it contains garbage in buffer from previous event. BIOS/ACPI on devices with WMI interface version 1 clears buffer and sometimes send more events in buffer at one call. Since commit 83fc44c32ad8 ("dell-wmi: Update code for processing WMI events") dell-wmi process all events in buffer (and not just first). So to prevent reading garbage from buffer we will process only first one event on devices with WMI interface version 0. Signed-off-by: Pali Rohár --- drivers/platform/x86/dell-wmi.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/platform/x86/dell-wmi.c b/drivers/platform/x86/dell-wmi.c index 09ee8ed..62f2f7a 100644 --- a/drivers/platform/x86/dell-wmi.c +++ b/drivers/platform/x86/dell-wmi.c @@ -237,6 +237,22 @@ static void dell_wmi_notify(u32 value, void *context) buffer_end = buffer_entry + buffer_size; + /* + * BIOS/ACPI on devices with WMI interface version 0 does not clear + * buffer before filling it. So next time when BIOS/ACPI send WMI event + * which is smaller as previous then it contains garbage in buffer from + * previous event. + * + * BIOS/ACPI on devices with WMI interface version 1 clears buffer and + * sometimes send more events in buffer at one call. + * + * So to prevent reading garbage from buffer we will process only first + * one event on devices with WMI interface version 0. + */ + if (dell_wmi_interface_version == 0 && buffer_entry < buffer_end) + if (buffer_end > buffer_entry + buffer_entry[0] + 1) + buffer_end = buffer_entry + buffer_entry[0] + 1; + while (buffer_entry < buffer_end) { len = buffer_entry[0]; -- 1.7.9.5