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Commit eb8fa317 authored by Takashi Iwai's avatar Takashi Iwai Committed by Greg Kroah-Hartman
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ASoC: Fix use-after-free at card unregistration 



commit 4efda5f2130da033aeedc5b3205569893b910de2 upstream.

soc_cleanup_card_resources() call snd_card_free() at the last of its
procedure.  This turned out to lead to a use-after-free.
PCM runtimes have been already removed via soc_remove_pcm_runtimes(),
while it's dereferenced later in soc_pcm_free() called via
snd_card_free().

The fix is simple: just move the snd_card_free() call to the beginning
of the whole procedure.  This also gives another benefit: it
guarantees that all operations have been shut down before actually
releasing the resources, which was racy until now.

Reported-and-tested-by: default avatarRobert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 82ecd2f0

sound/soc/soc-core.c

+3 −2
Original line number Diff line number Diff line
@@ -2076,6 +2076,9 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card) 
	list_for_each_entry(rtd, &card->rtd_list, list)

		flush_delayed_work(&rtd->delayed_work);



	/* free the ALSA card at first; this syncs with pending operations */

	snd_card_free(card->snd_card);



	/* remove and free each DAI */

	soc_remove_dai_links(card);

	soc_remove_pcm_runtimes(card);
@@ -2090,9 +2093,7 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card) 
	if (card->remove)

		card->remove(card);



	snd_card_free(card->snd_card);

	return 0;



}



/* removes a socdev */