[Asterisk-code-review] PJSIP XML, XPIDF: Fix buffer size overwrite memory corruptio... (asterisk[13])

[Richard Mudgett]

Richard Mudgett has uploaded a new change for review.

  https://gerrit.asterisk.org/802

Change subject: PJSIP XML, XPIDF: Fix buffer size overwrite memory corruption error.
......................................................................

PJSIP XML, XPIDF: Fix buffer size overwrite memory corruption error.

When res_pjsip body generator modules were generating XML or XPIDF
response bodies, there was a chance that the generated body would be the
exact size of the supplied buffer.  Adding the nul string terminator would
then write beyond the end of the buffer and potentially corrupt memory.

* Fix MALLOC_DEBUG high fence violations caused by adding a nul string
terminator on the end of a buffer for XML or XPIDF response bodies.

* Made calls to pj_xml_print() safer if the XML prolog is requested.  Due
to a bug in pjproject, the return value could be -1 _or_
AST_PJSIP_XML_PROLOG_LEN if the supplied buffer is not large enough.

* Updated the doxygen comment of AST_PJSIP_XML_PROLOG_LEN to describe the
return value of pj_xml_print() when the supplied buffer is not large
enough.

ASTERISK-25168
Reported by: Carl Fortin

Change-Id: Id70e1d373a6a2b2bd9e678b5cbc5e55b308981de
---
M include/asterisk/res_pjsip_presence_xml.h
M res/res_pjsip_dialog_info_body_generator.c
M res/res_pjsip_pidf_body_generator.c
M res/res_pjsip_pubsub.c
M res/res_pjsip_xpidf_body_generator.c
5 files changed, 19 insertions(+), 21 deletions(-)


  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/02/802/1

diff --git a/include/asterisk/res_pjsip_presence_xml.h b/include/asterisk/res_pjsip_presence_xml.h
index add5f89..deed090 100644
--- a/include/asterisk/res_pjsip_presence_xml.h
+++ b/include/asterisk/res_pjsip_presence_xml.h
@@ -17,14 +17,15 @@
  */
 
 /*!
- * \brief The length of the XML prolog when printing
- * presence or other XML in PJSIP.
+ * \brief Length of the XML prolog when printing presence or other XML in PJSIP.
  *
  * When calling any variant of pj_xml_print(), the documentation
  * claims that it will return -1 if the provided buffer is not
  * large enough. However, if the XML prolog is requested to be
- * printed, then the length of the XML prolog is returned upon
- * failure instead of -1.
+ * printed and the buffer is not large enough, then it will
+ * return -1 only if the buffer is not large enough to hold the
+ * XML prolog or return the length of the XML prolog on failure
+ * instead of -1.
  *
  * This constant is useful to check against when trying to determine
  * if printing XML succeeded or failed.
diff --git a/res/res_pjsip_dialog_info_body_generator.c b/res/res_pjsip_dialog_info_body_generator.c
index d9725f4..48ac60f 100644
--- a/res/res_pjsip_dialog_info_body_generator.c
+++ b/res/res_pjsip_dialog_info_body_generator.c
@@ -163,14 +163,13 @@
 	int size;
 
 	do {
-		size = pj_xml_print(dialog_info, ast_str_buffer(*str), ast_str_size(*str), PJ_TRUE);
-		if (size == AST_PJSIP_XML_PROLOG_LEN) {
+		size = pj_xml_print(dialog_info, ast_str_buffer(*str), ast_str_size(*str) - 1, PJ_TRUE);
+		if (size <= AST_PJSIP_XML_PROLOG_LEN) {
 			ast_str_make_space(str, ast_str_size(*str) * 2);
 			++growths;
 		}
-	} while (size == AST_PJSIP_XML_PROLOG_LEN && growths < MAX_STRING_GROWTHS);
-
-	if (size == AST_PJSIP_XML_PROLOG_LEN) {
+	} while (size <= AST_PJSIP_XML_PROLOG_LEN && growths < MAX_STRING_GROWTHS);
+	if (size <= AST_PJSIP_XML_PROLOG_LEN) {
 		ast_log(LOG_WARNING, "dialog-info+xml body text too large\n");
 		return;
 	}
diff --git a/res/res_pjsip_pidf_body_generator.c b/res/res_pjsip_pidf_body_generator.c
index ef0cce5..d3be8c1 100644
--- a/res/res_pjsip_pidf_body_generator.c
+++ b/res/res_pjsip_pidf_body_generator.c
@@ -84,19 +84,18 @@
 
 static void pidf_to_string(void *body, struct ast_str **str)
 {
-	int size;
-	int growths = 0;
 	pjpidf_pres *pres = body;
+	int growths = 0;
+	int size;
 
 	do {
 		size = pjpidf_print(pres, ast_str_buffer(*str), ast_str_size(*str) - 1);
-		if (size == AST_PJSIP_XML_PROLOG_LEN) {
+		if (size <= AST_PJSIP_XML_PROLOG_LEN) {
 			ast_str_make_space(str, ast_str_size(*str) * 2);
 			++growths;
 		}
-	} while (size == AST_PJSIP_XML_PROLOG_LEN && growths < MAX_STRING_GROWTHS);
-
-	if (size == AST_PJSIP_XML_PROLOG_LEN) {
+	} while (size <= AST_PJSIP_XML_PROLOG_LEN && growths < MAX_STRING_GROWTHS);
+	if (size <= AST_PJSIP_XML_PROLOG_LEN) {
 		ast_log(LOG_WARNING, "PIDF body text too large\n");
 		return;
 	}
diff --git a/res/res_pjsip_pubsub.c b/res/res_pjsip_pubsub.c
index c00bc76..650f5c5 100644
--- a/res/res_pjsip_pubsub.c
+++ b/res/res_pjsip_pubsub.c
@@ -1769,7 +1769,7 @@
 	pj_xml_node *rlmi = msg_body->data;
 
 	num_printed = pj_xml_print(rlmi, buf, size, PJ_TRUE);
-	if (num_printed == AST_PJSIP_XML_PROLOG_LEN) {
+	if (num_printed <= AST_PJSIP_XML_PROLOG_LEN) {
 		return -1;
 	}
 
diff --git a/res/res_pjsip_xpidf_body_generator.c b/res/res_pjsip_xpidf_body_generator.c
index 43cb1e7..298235c 100644
--- a/res/res_pjsip_xpidf_body_generator.c
+++ b/res/res_pjsip_xpidf_body_generator.c
@@ -106,14 +106,13 @@
 	int size;
 
 	do {
-		size = pjxpidf_print(pres, ast_str_buffer(*str), ast_str_size(*str));
-		if (size == AST_PJSIP_XML_PROLOG_LEN) {
+		size = pjxpidf_print(pres, ast_str_buffer(*str), ast_str_size(*str) - 1);
+		if (size <= AST_PJSIP_XML_PROLOG_LEN) {
 			ast_str_make_space(str, ast_str_size(*str) * 2);
 			++growths;
 		}
-	} while (size == AST_PJSIP_XML_PROLOG_LEN && growths < MAX_STRING_GROWTHS);
-
-	if (size == AST_PJSIP_XML_PROLOG_LEN) {
+	} while (size <= AST_PJSIP_XML_PROLOG_LEN && growths < MAX_STRING_GROWTHS);
+	if (size <= AST_PJSIP_XML_PROLOG_LEN) {
 		ast_log(LOG_WARNING, "XPIDF body text too large\n");
 		return;
 	}

-- 
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Gerrit-MessageType: newchange
Gerrit-Change-Id: Id70e1d373a6a2b2bd9e678b5cbc5e55b308981de
Gerrit-PatchSet: 1
Gerrit-Project: asterisk
Gerrit-Branch: 13
Gerrit-Owner: Richard Mudgett <rmudgett at digium.com>