From: Andre Noll <maan@systemlinux.org>
Date: Tue, 7 Aug 2012 11:51:47 +0000 (+0200)
Subject: osx_write: Be careful when dereferencing the private_data pointer.
X-Git-Tag: v0.4.12~8^2~1
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=831db326fc8977846792634c177c5811165c287a;ds=sidebyside

osx_write: Be careful when dereferencing the private_data pointer.

When the main process stops the audio unit the callback might be
sleeping on the mutex and run one more time.
---

diff --git a/osx_write.c b/osx_write.c
index 73aa1377..d278d02c 100644
--- a/osx_write.c
+++ b/osx_write.c
@@ -78,10 +78,14 @@ static OSStatus osx_callback(void *cb_arg, __a_unused AudioUnitRenderActionFlags
 {
 	int i;
 	struct writer_node *wn = cb_arg;
-	struct private_osx_write_data *powd = wn->private_data;
+	struct private_osx_write_data *powd;
 	size_t samples_have, samples_want = 0;
 
+	powd = wn->private_data;
 	mutex_lock(powd->mutex);
+	powd = wn->private_data;
+	if (!powd || !wn->btrn)
+		goto out;
 	/*
 	 * We fill with zeros if no data was yet written and we do not have
 	 * enough to fill all buffers.
@@ -322,18 +326,18 @@ static void osx_write_post_select(__a_unused struct sched *s, struct task *t)
 		btr_pushdown(btrn);
 	if (ret < 0 && need_drain_delay(powd))
 		ret = 0;
-	mutex_unlock(powd->mutex);
-
-	if (ret >= 0)
-		goto out;
+	if (ret >= 0) {
+		mutex_unlock(powd->mutex);
+		return;
+	}
 	AudioOutputUnitStop(powd->audio_unit);
 	AudioUnitUninitialize(powd->audio_unit);
 	CloseComponent(powd->audio_unit);
 	btr_remove_node(&powd->callback_btrn);
+	mutex_unlock(powd->mutex);
 remove_btrn:
 	btr_remove_node(&wn->btrn);
 	PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
-out:
 	t->error = ret;
 }