Commit d94815f9 authored Jun 28, 2017 by Takashi Iwai

ALSA: hda - Fix endless loop of codec configure



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: d068ebc2 ("ALSA: hda - Move some codes up to hdac_bus struct")
Reported-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent a8f20fd2

sound/pci/hda/hda_codec.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -295,6 +295,8 @@ 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)

sound/pci/hda/hda_controller.c

+6 −2

Original line number	Diff line number	Diff line
		@@ -1337,8 +1337,12 @@ 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;