This is a note to let you know that I've just added the patch titled
ASoC: Fix use-after-free at card unregistration
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
asoc-fix-use-after-free-at-card-unregistration.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4efda5f2130da033aeedc5b3205569893b910de2 Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@xxxxxxx>
Date: Wed, 24 May 2017 10:19:45 +0200
Subject: ASoC: Fix use-after-free at card unregistration
From: Takashi Iwai <tiwai@xxxxxxx>
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: Robert Jarzmik <robert.jarzmik@xxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/soc/soc-core.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -1868,6 +1868,9 @@ static int soc_cleanup_card_resources(st
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);
@@ -1879,9 +1882,7 @@ static int soc_cleanup_card_resources(st
snd_soc_dapm_free(&card->dapm);
- snd_card_free(card->snd_card);
return 0;
-
}
/* removes a socdev */
Patches currently in stable-queue which might be from tiwai@xxxxxxx are
queue-3.18/alsa-timer-fix-missing-queue-indices-reset-at-sndrv_timer_ioctl_select.patch
queue-3.18/asoc-fix-use-after-free-at-card-unregistration.patch