From: Takashi Iwai Date: Wed, 24 May 2017 08:19:45 +0000 (+0200) Subject: ASoC: Fix use-after-free at card unregistration X-Git-Url: http://git.lede-project.org./?a=commitdiff_plain;h=4efda5f2130da033aeedc5b3205569893b910de2;p=openwrt%2Fstaging%2Fblogic.git ASoC: Fix use-after-free at card unregistration 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 Signed-off-by: Takashi Iwai Signed-off-by: Mark Brown Cc: --- diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c index aae099c0e502..754e3ef8d7ae 100644 --- a/sound/soc/soc-core.c +++ b/sound/soc/soc-core.c @@ -2286,6 +2286,9 @@ 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); @@ -2300,9 +2303,7 @@ 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 */