xref: /third_party/libxml2/backport-malloc-fail-Fix-memory-leak-after-calling-valuePush.patch

From 85bc313e7996c06d52b6f6f5c6a467ff3a148e75 Mon Sep 17 00:00:00 2001
From: Nick Wellnhofer <wellnhofer@aevum.de>
Date: Wed, 15 Feb 2023 13:49:28 +0100
Subject: [PATCH] malloc-fail: Fix memory leak after calling valuePush

Destroy the object in valuePush if the function fails. This is somewhat
dangerous but matches the expectations of users.

Found with libFuzzer, see #344.

Reference:https://github.com/GNOME/libxml2/commit/85bc313e7996c06d52b6f6f5c6a467ff3a148e75
Conflict:NA
---
 xpath.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xpath.c b/xpath.c
index 7833870..dc99e63 100644
--- a/xpath.c
+++ b/xpath.c
@@ -2881,6 +2881,8 @@ valuePop(xmlXPathParserContextPtr ctxt)
  * a memory error is recorded in the parser context.
  *
  * Returns the number of items on the value stack, or -1 in case of error.
+ *
+ * The object is destroyed in case of error.
  */
 int
 valuePush(xmlXPathParserContextPtr ctxt, xmlXPathObjectPtr value)
@@ -2899,6 +2901,7 @@ valuePush(xmlXPathParserContextPtr ctxt, xmlXPathObjectPtr value)
 
         if (ctxt->valueMax >= XPATH_MAX_STACK_DEPTH) {
             xmlXPathPErrMemory(ctxt, "XPath stack depth limit reached\n");
+            xmlXPathFreeObject(value);
             return (-1);
         }
         tmp = (xmlXPathObjectPtr *) xmlRealloc(ctxt->valueTab,
@@ -2906,6 +2909,7 @@ valuePush(xmlXPathParserContextPtr ctxt, xmlXPathObjectPtr value)
                                              sizeof(ctxt->valueTab[0]));
         if (tmp == NULL) {
             xmlXPathPErrMemory(ctxt, "pushing value\n");
+            xmlXPathFreeObject(value);
             return (-1);
         }
         ctxt->valueMax *= 2;
-- 
2.27.0