From a9ac889b4c4a42ce4367243c9e1afbe29c61fabd Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Tue, 29 Mar 2022 15:55:10 +0200 Subject: [PATCH] Revert "Revert "ALSA: pcm: Fix races among concurrent prepare and hw_params/hw_free calls"" This reverts commit f9e40dc81261c1a04ec8637244dcaa443db95e30. It fixes CVE-2022-1048 and it had to originally be reverted due to ABI issues. Add it back now as the ABI "break" is allowed and we want to fix this real problem. Signed-off-by: Greg Kroah-Hartman Change-Id: Ife1c36ac31c25f77aab42b7d96e9552d4acc3184 --- sound/core/pcm_native.c | 32 ++++++++++++++++++-------------- 1 file changed, 18 insertions(+), 14 deletions(-) diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 9ea2dbbd91aa..5cac630a141c 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -1177,15 +1177,17 @@ struct action_ops { static int snd_pcm_action_group(const struct action_ops *ops, struct snd_pcm_substream *substream, snd_pcm_state_t state, - bool do_lock) + bool stream_lock) { struct snd_pcm_substream *s = NULL; struct snd_pcm_substream *s1; int res = 0, depth = 1; snd_pcm_group_for_each_entry(s, substream) { - if (do_lock && s != substream) { - if (s->pcm->nonatomic) + if (s != substream) { + if (!stream_lock) + mutex_lock_nested(&s->runtime->buffer_mutex, depth); + else if (s->pcm->nonatomic) mutex_lock_nested(&s->self_group.mutex, depth); else spin_lock_nested(&s->self_group.lock, depth); @@ -1213,18 +1215,18 @@ static int snd_pcm_action_group(const struct action_ops *ops, ops->post_action(s, state); } _unlock: - if (do_lock) { - /* unlock streams */ - snd_pcm_group_for_each_entry(s1, substream) { - if (s1 != substream) { - if (s1->pcm->nonatomic) - mutex_unlock(&s1->self_group.mutex); - else - spin_unlock(&s1->self_group.lock); - } - if (s1 == s) /* end */ - break; + /* unlock streams */ + snd_pcm_group_for_each_entry(s1, substream) { + if (s1 != substream) { + if (!stream_lock) + mutex_unlock(&s1->runtime->buffer_mutex); + else if (s1->pcm->nonatomic) + mutex_unlock(&s1->self_group.mutex); + else + spin_unlock(&s1->self_group.lock); } + if (s1 == s) /* end */ + break; } return res; } @@ -1354,10 +1356,12 @@ static int snd_pcm_action_nonatomic(const struct action_ops *ops, /* Guarantee the group members won't change during non-atomic action */ down_read(&snd_pcm_link_rwsem); + mutex_lock(&substream->runtime->buffer_mutex); if (snd_pcm_stream_linked(substream)) res = snd_pcm_action_group(ops, substream, state, false); else res = snd_pcm_action_single(ops, substream, state); + mutex_unlock(&substream->runtime->buffer_mutex); up_read(&snd_pcm_link_rwsem); return res; }