File _service:obs_scm:CVE-2021-33391.patch of Package tidy

Origin: https://launchpadlibrarian.net/697070499/tidy-html5_2%3A5.6.0-11_2%3A5.6.0-11ubuntu0.20.04.1.diff.gz

Backport of:

From efa61528aa500a1efbd2768121820742d3bb709b Mon Sep 17 00:00:00 2001
From: Jim Derry <balthisar@gmail.com>
Date: Sat, 31 Jul 2021 08:26:16 -0400
Subject: [PATCH] Fixes #946 by refactoring the recursion into a loop with a
 heap-based stack.

---
 .../cases/github-cases/case-946.conf          |   3 +
 .../cases/github-cases/case-946@1.html        | Bin 0 -> 11558 bytes
 .../cases/github-expects/case-946.html        |  44 +++
 .../cases/github-expects/case-946.txt         | 330 ++++++++++++++++++
 src/gdoc.c                                    |  13 +-
 version.txt                                   |   4 +-
 6 files changed, 388 insertions(+), 6 deletions(-)
 create mode 100755 regression_testing/cases/github-cases/case-946.conf
 create mode 100644 regression_testing/cases/github-cases/case-946@1.html
 create mode 100644 regression_testing/cases/github-expects/case-946.html
 create mode 100644 regression_testing/cases/github-expects/case-946.txt

diff --git a/src/gdoc.c b/src/gdoc.c
index 50cd9bc33..8f5f8ffd7 100644
--- a/src/gdoc.c
+++ b/src/gdoc.c
@@ -96,14 +96,15 @@ static void DiscardContainer( TidyDocImpl* doc, Node *element, Node **pnode)
 
 static void CleanNode( TidyDocImpl* doc, Node *node )
 {
+    Stack *stack = TY_(newStack)(doc, 16);
     Node *child, *next;
 
-    if (node->content)
+    if ( (child = node->content) )
     {
-        for (child = node->content; child != NULL; child = next)
+        while (child)
         {
             next = child->next;
-
+            
             if (TY_(nodeIsElement)(child))
             {
                 if (nodeIsSTYLE(child))
@@ -131,10 +132,14 @@ static void CleanNode( TidyDocImpl* doc, Node *node )
                     if (child->attributes)
                         TY_(DropAttrByName)( doc, child, "class" );
 
-                    CleanNode(doc, child);
+                    TY_(push)(stack,next);
+                    child = child->content;
+                    continue;
                 }
             }
+            child = next ? next : TY_(pop)(stack);
         }
+        TY_(freeStack)(stack);
     }
 }