Merged revisions 264331 via svnmerge from

https://origsvn.digium.com/svn/asterisk/trunk

........
  r264331 | dvossel | 2010-05-19 14:21:04 -0500 (Wed, 19 May 2010) | 13 lines
  
  fixes crash in check_rtp_timeout
  
  During deadlock avoidance the sip dialog pvt is locked and
  unlocked.  When this occurs we have no guarantee the pvt's owner
  is still valid.  We were trying to access the pvt's owner after
  this without checking to see if it still existed first. 
  
  (closes issue #17271)
  Reported by: under
  Patches:
        check_rtp_timeout.diff uploaded by under (license 914)
  Tested by: dvossel
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.2@264332 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -22475,6 +22475,9 @@ static void check_rtp_timeout(struct sip_pvt *dialog, time_t t)
 					usleep(1);
 					sip_pvt_lock(dialog);
 				}
+				if (!dialog->owner) {
+					return; /* channel hangup can occur during deadlock avoidance. */
+				}
 				ast_log(LOG_NOTICE, "Disconnecting call '%s' for lack of RTP activity in %ld seconds\n",
 					dialog->owner->name, (long) (t - dialog->lastrtprx));
 				/* Issue a softhangup */