Protect ast_filestream object when on a channel

The ast_filestream object gets tacked on to a channel via
chan->timingdata.  It's a reference counted object, but the reference
count isn't used when putting it on a channel.  It's theoretically
possible for another thread to interfere with the channel while it's
unlocked and cause the filestream to get destroyed.

Use the astobj2 reference count to make sure that as long as this code
path is holding on the ast_filestream and passing it into the file.c
playback code, that it knows it's valid.

Bug reported by Leif Madsen.

Review: https://reviewboard.asterisk.org/r/3135/
........

Merged revisions 406566 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 406567 from http://svn.asterisk.org/svn/asterisk/branches/11
........

Merged revisions 406574 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@406595 65c4cc65-6c06-0410-ace0-fbb531ad65f3

3 files changed, 30 insertions, 1 deletions

diff --git a/include/asterisk/channel.h b/include/asterisk/channel.h
index 5b042a96d..106117de1 100644
--- a/include/asterisk/channel.h
+++ b/include/asterisk/channel.h
@@ -929,6 +929,10 @@ enum {
 	 * publish.
 	 */
 	AST_FLAG_SNAPSHOT_STAGE = (1 << 25),
+	/*!
+	 * The data on chan->timingdata is an astobj2 object.
+	 */
+	AST_FLAG_TIMINGDATA_IS_AO2_OBJ = (1 << 26),
 };
 
 /*! \brief ast_bridge_config flags */
@@ -2275,6 +2279,7 @@ int ast_autoservice_ignore(struct ast_channel *chan, enum ast_frame_type ftype);
  * \version 1.6.1 changed samples parameter to rate, accomodates new timing methods
  */
 int ast_settimeout(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data);
+int ast_settimeout_full(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data, unsigned int is_ao2_obj);
 
 /*!
  * \brief Transfer a channel (if supported).
diff --git a/main/channel.c b/main/channel.c
index 567d8c621..a9f0fbb34 100644
--- a/main/channel.c
+++ b/main/channel.c
@@ -3421,6 +3421,11 @@ int ast_waitfordigit(struct ast_channel *c, int ms)
 
 int ast_settimeout(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data)
 {
+	return ast_settimeout_full(c, rate, func, data, 0);
+}
+
+int ast_settimeout_full(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data, unsigned int is_ao2_obj)
+{
 	int res;
 	unsigned int real_rate = rate, max_rate;
 
@@ -3444,9 +3449,20 @@ int ast_settimeout(struct ast_channel *c, unsigned int rate, int (*func)(const v
 
 	res = ast_timer_set_rate(ast_channel_timer(c), real_rate);
 
+	if (ast_channel_timingdata(c) && ast_test_flag(ast_channel_flags(c), AST_FLAG_TIMINGDATA_IS_AO2_OBJ)) {
+		ao2_ref(ast_channel_timingdata(c), -1);
+	}
+
 	ast_channel_timingfunc_set(c, func);
 	ast_channel_timingdata_set(c, data);
 
+	if (data && is_ao2_obj) {
+		ao2_ref(data, 1);
+		ast_set_flag(ast_channel_flags(c), AST_FLAG_TIMINGDATA_IS_AO2_OBJ);
+	} else {
+		ast_clear_flag(ast_channel_flags(c), AST_FLAG_TIMINGDATA_IS_AO2_OBJ);
+	}
+
 	if (func == NULL && rate == 0 && ast_channel_fdno(c) == AST_TIMING_FD) {
 		/* Clearing the timing func and setting the rate to 0
 		 * means that we don't want to be reading from the timingfd
@@ -3795,9 +3811,17 @@ static struct ast_frame *__ast_read(struct ast_channel *chan, int dropaudio)
 				/* save a copy of func/data before unlocking the channel */
 				ast_timing_func_t func = ast_channel_timingfunc(chan);
 				void *data = ast_channel_timingdata(chan);
+				int got_ref = 0;
+				if (data && ast_test_flag(ast_channel_flags(chan), AST_FLAG_TIMINGDATA_IS_AO2_OBJ)) {
+					ao2_ref(data, 1);
+					got_ref = 1;
+				}
 				ast_channel_fdno_set(chan, -1);
 				ast_channel_unlock(chan);
 				func(data);
+				if (got_ref) {
+					ao2_ref(data, -1);
+				}
 			} else {
 				ast_timer_set_rate(ast_channel_timer(chan), 0);
 				ast_channel_fdno_set(chan, -1);
diff --git a/main/file.c b/main/file.c
index ffdbf1821..458f25446 100644
--- a/main/file.c
+++ b/main/file.c
@@ -902,7 +902,7 @@ static enum fsread_res ast_readaudio_callback(struct ast_filestream *s)
 
 			rate = (unsigned int) roundf(samp_rate / ((float) whennext));
 
-			ast_settimeout(s->owner, rate, ast_fsread_audio, s);
+			ast_settimeout_full(s->owner, rate, ast_fsread_audio, s, 1);
 		} else {
 			ast_channel_streamid_set(s->owner, ast_sched_add(ast_channel_sched(s->owner), whennext / (ast_format_rate(&s->fmt->format) / 1000), ast_fsread_audio, s));
 		}