Merged revisions 209235 via svnmerge from

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

........
  r209235 | mmichelson | 2009-07-27 15:54:54 -0500 (Mon, 27 Jul 2009) | 5 lines
  
  Gracefully handle malformed RTP text packets.
  
  AST-2009-004
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git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/1.6.1@209237 65c4cc65-6c06-0410-ace0-fbb531ad65f3

main/rtp.c

@@ -1840,6 +1840,9 @@ struct ast_frame *ast_rtp_read(struct ast_rtp *rtp)
 
 		rtp->f.subclass = AST_FORMAT_T140;
 		header_end = memchr(data, ((*data) & 0x7f), rtp->f.datalen);
+		if (header_end == NULL) {
+			return &ast_null_frame;
+		}
 		header_end++;
 		
 		header_length = header_end - data;