Commit 807c3cc0 authored by Takashi Iwai's avatar Takashi Iwai Committed by Ben Hutchings

ASoC: Fix use-after-free at card unregistration

commit 4efda5f2 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>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 559211ac
...@@ -1574,6 +1574,9 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card) ...@@ -1574,6 +1574,9 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card)
flush_delayed_work_sync(&rtd->delayed_work); flush_delayed_work_sync(&rtd->delayed_work);
} }
/* free the ALSA card at first; this syncs with pending operations */
snd_card_free(card->snd_card);
/* remove auxiliary devices */ /* remove auxiliary devices */
for (i = 0; i < card->num_aux_devs; i++) for (i = 0; i < card->num_aux_devs; i++)
soc_remove_aux_dev(card, i); soc_remove_aux_dev(card, i);
...@@ -1590,9 +1593,7 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card) ...@@ -1590,9 +1593,7 @@ static int soc_cleanup_card_resources(struct snd_soc_card *card)
snd_soc_dapm_free(&card->dapm); snd_soc_dapm_free(&card->dapm);
kfree(card->rtd); kfree(card->rtd);
snd_card_free(card->snd_card);
return 0; return 0;
} }
/* removes a socdev */ /* removes a socdev */
......
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