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authorTakashi Iwai <tiwai@suse.de>2008-09-25 08:51:03 -0400
committerTakashi Iwai <tiwai@suse.de>2008-09-25 08:51:03 -0400
commit399ccdc1cd4e92e541d4dacbbf18c52bd693418b (patch)
tree4e9ecc896adb79397166c02bdd4cedd690a54a98
parentb0b8daf7849cc98217ca018fbe82c61cd2b735bc (diff)
ALSA: fix locking in snd_pcm_open*() and snd_rawmidi_open*()
The PCM and rawmidi open callbacks have a lock against card->controls_list but it takes a wrong one, card->controls_rwsem, instead of a right one card->ctl_files_rwlock. This patch fixes them. This change also fixes automatically the potential deadlocks due to mm->mmap_sem in munmap and copy_from/to_user, reported by Sitsofe Wheeler: A: snd_ctl_elem_user_tlv(): card->controls_rwsem => mm->mmap_sem B: snd_pcm_open(): card->open_mutex => card->controls_rwsem C: munmap: mm->mmap_sem => snd_pcm_release(): card->open_mutex The patch breaks the chain. Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/core/pcm.c4
-rw-r--r--sound/core/rawmidi.c4
2 files changed, 4 insertions, 4 deletions
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 9dd9bc73fe1d..ece25c718e95 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -781,7 +781,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
781 return -ENODEV; 781 return -ENODEV;
782 782
783 card = pcm->card; 783 card = pcm->card;
784 down_read(&card->controls_rwsem); 784 read_lock(&card->ctl_files_rwlock);
785 list_for_each_entry(kctl, &card->ctl_files, list) { 785 list_for_each_entry(kctl, &card->ctl_files, list) {
786 if (kctl->pid == current->pid) { 786 if (kctl->pid == current->pid) {
787 prefer_subdevice = kctl->prefer_pcm_subdevice; 787 prefer_subdevice = kctl->prefer_pcm_subdevice;
@@ -789,7 +789,7 @@ int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
789 break; 789 break;
790 } 790 }
791 } 791 }
792 up_read(&card->controls_rwsem); 792 read_unlock(&card->ctl_files_rwlock);
793 793
794 switch (stream) { 794 switch (stream) {
795 case SNDRV_PCM_STREAM_PLAYBACK: 795 case SNDRV_PCM_STREAM_PLAYBACK:
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index f7ea7287c59c..b917a9f981c7 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -418,7 +418,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
418 mutex_lock(&rmidi->open_mutex); 418 mutex_lock(&rmidi->open_mutex);
419 while (1) { 419 while (1) {
420 subdevice = -1; 420 subdevice = -1;
421 down_read(&card->controls_rwsem); 421 read_lock(&card->ctl_files_rwlock);
422 list_for_each_entry(kctl, &card->ctl_files, list) { 422 list_for_each_entry(kctl, &card->ctl_files, list) {
423 if (kctl->pid == current->pid) { 423 if (kctl->pid == current->pid) {
424 subdevice = kctl->prefer_rawmidi_subdevice; 424 subdevice = kctl->prefer_rawmidi_subdevice;
@@ -426,7 +426,7 @@ static int snd_rawmidi_open(struct inode *inode, struct file *file)
426 break; 426 break;
427 } 427 }
428 } 428 }
429 up_read(&card->controls_rwsem); 429 read_unlock(&card->ctl_files_rwlock);
430 err = snd_rawmidi_kernel_open(rmidi->card, rmidi->device, 430 err = snd_rawmidi_kernel_open(rmidi->card, rmidi->device,
431 subdevice, fflags, rawmidi_file); 431 subdevice, fflags, rawmidi_file);
432 if (err >= 0) 432 if (err >= 0)