From dd9c654019aa4fc8840085917be7f3243fd452fc Mon Sep 17 00:00:00 2001
From: "Randall S. Becker" <randall.becker@nexbridge.ca>
Date: Thu, 8 Aug 2024 07:28:26 -0400
Subject: [PATCH] Add guard code to prevent the use of NULL pointers in
 emitter.c

This is related to CVE-2024-35326

Fixes #301

Signed-off-by: Randall S. Becker <randall.becker@nexbridge.ca>
---
 src/emitter.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/src/emitter.c b/src/emitter.c
index 609b28a4..28bcd11b 100644
--- a/src/emitter.c
+++ b/src/emitter.c
@@ -391,7 +391,9 @@ yaml_emitter_append_tag_directive(yaml_emitter_t *emitter,
 
 error:
     yaml_free(copy.handle);
+    copy.handle = NULL;
     yaml_free(copy.prefix);
+    copy.prefix = NULL;
     return 0;
 }
 
@@ -727,7 +729,9 @@ yaml_emitter_emit_document_end(yaml_emitter_t *emitter,
             yaml_tag_directive_t tag_directive = POP(emitter,
                     emitter->tag_directives);
             yaml_free(tag_directive.handle);
+            tag_directive.handle = NULL;
             yaml_free(tag_directive.prefix);
+            tag_directive.prefix = NULL;
         }
 
         return 1;
@@ -1812,6 +1816,8 @@ yaml_emitter_write_indicator(yaml_emitter_t *emitter,
     size_t indicator_length;
     yaml_string_t string;
 
+    if (!indicator)
+    	return 0;
     indicator_length = strlen(indicator);
     STRING_ASSIGN(string, (yaml_char_t *)indicator, indicator_length);
 
@@ -1834,6 +1840,9 @@ yaml_emitter_write_anchor(yaml_emitter_t *emitter,
         yaml_char_t *value, size_t length)
 {
     yaml_string_t string;
+    if (!value || length < 1)
+    	return 0;
+
     STRING_ASSIGN(string, value, length);
 
     while (string.pointer != string.end) {
@@ -1851,6 +1860,9 @@ yaml_emitter_write_tag_handle(yaml_emitter_t *emitter,
         yaml_char_t *value, size_t length)
 {
     yaml_string_t string;
+
+    if (!value || length < 1)
+    	return 0;
     STRING_ASSIGN(string, value, length);
 
     if (!emitter->whitespace) {
@@ -1873,6 +1885,9 @@ yaml_emitter_write_tag_content(yaml_emitter_t *emitter,
         int need_whitespace)
 {
     yaml_string_t string;
+
+    if (!value || length < 1)
+    	return 0;
     STRING_ASSIGN(string, value, length);
 
     if (need_whitespace && !emitter->whitespace) {
@@ -1923,6 +1938,9 @@ yaml_emitter_write_plain_scalar(yaml_emitter_t *emitter,
     int spaces = 0;
     int breaks = 0;
 
+    if (!value || length < 1)
+    	return 0;
+
     STRING_ASSIGN(string, value, length);
 
     /**
@@ -1989,6 +2007,9 @@ yaml_emitter_write_single_quoted_scalar(yaml_emitter_t *emitter,
     int spaces = 0;
     int breaks = 0;
 
+    if (!value || length < 1)
+    	return 0;
+
     STRING_ASSIGN(string, value, length);
 
     if (!yaml_emitter_write_indicator(emitter, "'", 1, 0, 0))
@@ -2054,6 +2075,8 @@ yaml_emitter_write_double_quoted_scalar(yaml_emitter_t *emitter,
     yaml_string_t string;
     int spaces = 0;
 
+    if (!value || length < 1)
+    	return 0;
     STRING_ASSIGN(string, value, length);
 
     if (!yaml_emitter_write_indicator(emitter, "\"", 1, 0, 0))
@@ -2268,6 +2291,8 @@ yaml_emitter_write_literal_scalar(yaml_emitter_t *emitter,
     yaml_string_t string;
     int breaks = 1;
 
+    if (!value || length < 1)
+    	return 0;
     STRING_ASSIGN(string, value, length);
 
     if (!yaml_emitter_write_indicator(emitter, "|", 1, 0, 0))
@@ -2308,6 +2333,8 @@ yaml_emitter_write_folded_scalar(yaml_emitter_t *emitter,
     int breaks = 1;
     int leading_spaces = 1;
 
+    if (!value || length < 1)
+    	return 0;
     STRING_ASSIGN(string, value, length);
 
     if (!yaml_emitter_write_indicator(emitter, ">", 1, 0, 0))