Merged revisions 328608 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.8

........
  r328608 | markm | 2011-07-18 08:35:57 -0400 (Mon, 18 Jul 2011) | 9 lines
  
  If the sip private structure is null, sip_setoption() will defref the null pointer and crash.
  
  Ideally, sip_setoption shouldn't be called if there is a lack of a sip private structure.  But this will fix a crash.
  
  (closes issue ASTERISK-17909)
  Reported by: Mark Murawski
  Tested by: Mark Murawski
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.10@328611 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -4266,6 +4266,11 @@ static int sip_setoption(struct ast_channel *chan, int option, void *data, int d
 	int res = -1;
 	struct sip_pvt *p = chan->tech_pvt;
 
+        if (!p) {
+        	ast_log(LOG_ERROR, "Attempt to Ref a null pointer.  sip private structure is gone!\n");
+        	return -1;
+        }
+
 	sip_pvt_lock(p);
 
 	switch (option) {