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Commit 9a938895 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 54d12fbf

sound/soc/soc-core.c

+3 −2
Original line number Diff line number Diff line
@@ -1775,6 +1775,9 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card) 
	for (i = 0; i < card->num_aux_devs; i++)

		soc_remove_aux_dev(card, i);



	/* 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);
@@ -1786,9 +1789,7 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card) 


	snd_soc_dapm_free(&card->dapm);



	snd_card_free(card->snd_card);

	return 0;



}



/* removes a socdev */