ALSA: pcm: oss: Fix race at SNDCTL_DSP_SETTRIGGER There is a small race window at snd_pcm_oss_set_trigger() that is called from OSS PCM SNDCTL_DSP_SETTRIGGER ioctl; namely the function calls snd_pcm_oss_make_ready() at first, then takes the params_lock mu

Commit Message

Ma Ke Sept. 20, 2023, 2:35 a.m. UTC

The fix is simply to cover snd_pcm_oss_make_ready() call into the same
params_lock mutex with snd_pcm_oss_make_ready_locked() variant.

Signed-off-by: Ma Ke <[e-mail]>
---
 sound/core/oss/pcm_oss.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

Patch

diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 728c211142d1..9a830aeeba63 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -2083,21 +2083,14 @@  static int snd_pcm_oss_set_trigger(struct snd_pcm_oss_file *pcm_oss_file, int tr
 	psubstream = pcm_oss_file->streams[SNDRV_PCM_STREAM_PLAYBACK];
 	csubstream = pcm_oss_file->streams[SNDRV_PCM_STREAM_CAPTURE];
 
-	if (psubstream) {
-		err = snd_pcm_oss_make_ready(psubstream);
-		if (err < 0)
-			return err;
-	}
-	if (csubstream) {
-		err = snd_pcm_oss_make_ready(csubstream);
-		if (err < 0)
-			return err;
-	}
       	if (psubstream) {
       		runtime = psubstream->runtime;
 		cmd = 0;
 		if (mutex_lock_interruptible(&runtime->oss.params_lock))
 			return -ERESTARTSYS;
+		err = snd_pcm_oss_make_ready_locked(psubstream);
+		if (err < 0)
+			goto _skip1;
 		if (trigger & PCM_ENABLE_OUTPUT) {
 			if (runtime->oss.trigger)
 				goto _skip1;
@@ -2128,6 +2121,9 @@  static int snd_pcm_oss_set_trigger(struct snd_pcm_oss_file *pcm_oss_file, int tr
 		cmd = 0;
 		if (mutex_lock_interruptible(&runtime->oss.params_lock))
 			return -ERESTARTSYS;
+		err = snd_pcm_oss_make_ready_locked(csubstream);
+		if (err < 0)
+			goto _skip2;
 		if (trigger & PCM_ENABLE_INPUT) {
 			if (runtime->oss.trigger)
 				goto _skip2;