Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755580AbdGCNly (ORCPT ); Mon, 3 Jul 2017 09:41:54 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:35840 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755283AbdGCNlu (ORCPT ); Mon, 3 Jul 2017 09:41:50 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Daniel Vetter , Takashi Iwai Subject: [PATCH 4.9 037/172] ALSA: hda - Fix endless loop of codec configure Date: Mon, 3 Jul 2017 15:33:37 +0200 Message-Id: <20170703133415.979264316@linuxfoundation.org> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170703133414.260777365@linuxfoundation.org> References: <20170703133414.260777365@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2220 Lines: 61 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit d94815f917da770d42c377786dc428f542e38f71 upstream. azx_codec_configure() loops over the codecs found on the given controller via a linked list. The code used to work in the past, but in the current version, this may lead to an endless loop when a codec binding returns an error. The culprit is that the snd_hda_codec_configure() unregisters the device upon error, and this eventually deletes the given codec object from the bus. Since the list is initialized via list_del_init(), the next object points to the same device itself. This behavior change was introduced at splitting the HD-audio code code, and forgotten to adapt it here. For fixing this bug, just use a *_safe() version of list iteration. Fixes: d068ebc25e6e ("ALSA: hda - Move some codes up to hdac_bus struct") Reported-by: Daniel Vetter Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/pci/hda/hda_codec.h | 2 ++ sound/pci/hda/hda_controller.c | 8 ++++++-- 2 files changed, 8 insertions(+), 2 deletions(-) --- a/sound/pci/hda/hda_codec.h +++ b/sound/pci/hda/hda_codec.h @@ -294,6 +294,8 @@ struct hda_codec { #define list_for_each_codec(c, bus) \ list_for_each_entry(c, &(bus)->core.codec_list, core.list) +#define list_for_each_codec_safe(c, n, bus) \ + list_for_each_entry_safe(c, n, &(bus)->core.codec_list, core.list) /* snd_hda_codec_read/write optional flags */ #define HDA_RW_NO_RESPONSE_FALLBACK (1 << 0) --- a/sound/pci/hda/hda_controller.c +++ b/sound/pci/hda/hda_controller.c @@ -1333,8 +1333,12 @@ EXPORT_SYMBOL_GPL(azx_probe_codecs); /* configure each codec instance */ int azx_codec_configure(struct azx *chip) { - struct hda_codec *codec; - list_for_each_codec(codec, &chip->bus) { + struct hda_codec *codec, *next; + + /* use _safe version here since snd_hda_codec_configure() deregisters + * the device upon error and deletes itself from the bus list. + */ + list_for_each_codec_safe(codec, next, &chip->bus) { snd_hda_codec_configure(codec); } return 0;