From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bartlomiej Zolnierkiewicz Subject: [PATCH] acpi: fix NULL pointer dereference in acpi_ex_release_mutex() Date: Sat, 25 Jul 2009 18:01:18 +0200 Message-ID: <200907251801.19482.bzolnier@gmail.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT Return-path: Received: from mail-bw0-f228.google.com ([209.85.218.228]:36348 "EHLO mail-bw0-f228.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751299AbZGYQEL convert rfc822-to-8bit (ORCPT ); Sat, 25 Jul 2009 12:04:11 -0400 Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Len Brown Cc: linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, Dan Carpenter , corbet@lwn.net, eteo@redhat.com From: Bartlomiej Zolnierkiewicz Subject: [PATCH] acpi: fix NULL pointer dereference in acpi_ex_release_mutex() >>From Dan's list: drivers/acpi/acpica/exmutex.c +397 acpi_ex_release_mutex(40) warning: variable derefenced before check 'walk_state->thread' Reorder the code to make it check for walk_state->thread existence before accessing walk_state->thread->thread_id and fix the comment while at it. Reported-by: Dan Carpenter Cc: corbet@lwn.net Cc: eteo@redhat.com Signed-off-by: Bartlomiej Zolnierkiewicz --- 2.6.31 material drivers/acpi/acpica/exmutex.c | 17 ++++++++--------- 1 file changed, 8 insertions(+), 9 deletions(-) Index: b/drivers/acpi/acpica/exmutex.c =================================================================== --- a/drivers/acpi/acpica/exmutex.c +++ b/drivers/acpi/acpica/exmutex.c @@ -375,6 +375,14 @@ acpi_ex_release_mutex(union acpi_operand return_ACPI_STATUS(AE_AML_MUTEX_NOT_ACQUIRED); } + /* must have a valid thread */ + if (!walk_state->thread) { + ACPI_ERROR((AE_INFO, + "Cannot release Mutex [%4.4s], null thread info", + acpi_ut_get_node_name(obj_desc->mutex.node))); + return_ACPI_STATUS(AE_AML_INTERNAL); + } + /* * The Mutex is owned, but this thread must be the owner. * Special case for Global Lock, any thread can release @@ -392,15 +400,6 @@ acpi_ex_release_mutex(union acpi_operand return_ACPI_STATUS(AE_AML_NOT_OWNER); } - /* Must have a valid thread ID */ - - if (!walk_state->thread) { - ACPI_ERROR((AE_INFO, - "Cannot release Mutex [%4.4s], null thread info", - acpi_ut_get_node_name(obj_desc->mutex.node))); - return_ACPI_STATUS(AE_AML_INTERNAL); - } - /* * The sync level of the mutex must be equal to the current sync level. In * other words, the current level means that at least one mutex at that