3.2.93-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Takashi Iwai <[email protected]> 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 <[email protected]> Signed-off-by: Takashi Iwai <[email protected]> Signed-off-by: Mark Brown <[email protected]> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- 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 @@ -1574,6 +1574,9 @@ static int soc_cleanup_card_resources(st 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 */ for (i = 0; i < card->num_aux_devs; i++) soc_remove_aux_dev(card, i); @@ -1590,9 +1593,7 @@ static int soc_cleanup_card_resources(st snd_soc_dapm_free(&card->dapm); kfree(card->rtd); - snd_card_free(card->snd_card); return 0; - } /* removes a socdev */
