+From f0c717463d569f87a16f9b014033c8ca8939a7b4 Mon Sep 17 00:00:00 2001
+From: Mark Michelson <mmichelson@digium.com>
+Date: Thu, 13 Apr 2017 16:59:40 -0500
+Subject: [PATCH] Parse zero-length multipart body parts correctly.
+
+The calculation of end_body could result in a negative length being
+passed to multipart_body_parse_part().
+---
+ pjsip/src/pjsip/sip_multipart.c | 16 +++++++++-------
+ 1 file changed, 9 insertions(+), 7 deletions(-)
+
+--- a/pjsip/src/pjsip/sip_multipart.c
++++ b/pjsip/src/pjsip/sip_multipart.c
+@@ -646,13 +646,15 @@ PJ_DEF(pjsip_msg_body*) pjsip_multipart_
+
+ end_body = curptr;
+
+- /* The newline preceeding the delimiter is conceptually part of
+- * the delimiter, so trim it from the body.
+- */
+- if (*(end_body-1) == '\n')
+- --end_body;
+- if (*(end_body-1) == '\r')
+- --end_body;
++ if (end_body > start_body) {
++ /* The newline preceeding the delimiter is conceptually part of
++ * the delimiter, so trim it from the body.
++ */
++ if (*(end_body-1) == '\n')
++ --end_body;
++ if (*(end_body-1) == '\r')
++ --end_body;
++ }
+
+ /* Now that we have determined the part's boundary, parse it
+ * to get the header and body part of the part.