From: Matthew Nicholson <mnicholson@digium.com>
Date: Tue, 29 Sep 2009 20:25:14 +0000 (+0000)
Subject: Avoid a deadlock in chanspy, just in case the spyee is masqueraded and chanspy_ds_cha... 
X-Git-Tag: 1.6.1.7-rc2~25
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=185e4321a73a922ef5062b850cf25409eb0be50f;p=thirdparty%2Fasterisk.git

Avoid a deadlock in chanspy, just in case the spyee is masqueraded and chanspy_ds_chan_fixup() is called with the channel locked.

(closes issue #15965)
Reported by: atis
Patches:
      chanspy-deadlock-fix1.diff uploaded by mnicholson (license 96)
Tested by: atis


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.1@220938 65c4cc65-6c06-0410-ace0-fbb531ad65f3
---

diff --git a/apps/app_chanspy.c b/apps/app_chanspy.c
index 7317e35785..0932a842d1 100644
--- a/apps/app_chanspy.c
+++ b/apps/app_chanspy.c
@@ -337,9 +337,10 @@ static int channel_spy(struct ast_channel *chan, struct chanspy_ds *spyee_chansp
 	ast_channel_unlock(chan);
 
 	ast_mutex_lock(&spyee_chanspy_ds->lock);
-	if (spyee_chanspy_ds->chan) {
-		spyee = spyee_chanspy_ds->chan;
-		ast_channel_lock(spyee);
+	while ((spyee = spyee_chanspy_ds->chan) && ast_channel_trylock(spyee)) {
+		/* avoid a deadlock here, just in case spyee is masqueraded and
+		 * chanspy_ds_chan_fixup() is called with the channel locked */
+		DEADLOCK_AVOIDANCE(&spyee_chanspy_ds->lock);
 	}
 	ast_mutex_unlock(&spyee_chanspy_ds->lock);