From 99ed43280dec1eec088bbf4242105c0953924e39 Mon Sep 17 00:00:00 2001
From: Dentomologist <dentomologist@gmail.com>
Date: Mon, 24 May 2021 09:44:21 -0700
Subject: [PATCH] Updater: Escape HTML characters in commit descriptions

---
 Source/Core/Common/StringUtil.cpp          | 19 +++++++++++++++++++
 Source/Core/Common/StringUtil.h            |  2 ++
 Source/Core/UICommon/AutoUpdate.cpp        |  6 +++---
 Source/UnitTests/Common/StringUtilTest.cpp | 10 ++++++++++
 4 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/Source/Core/Common/StringUtil.cpp b/Source/Core/Common/StringUtil.cpp
index 9c57bf944a..77fcd731a1 100644
--- a/Source/Core/Common/StringUtil.cpp
+++ b/Source/Core/Common/StringUtil.cpp
@@ -5,6 +5,7 @@
 #include "Common/StringUtil.h"
 
 #include <algorithm>
+#include <array>
 #include <codecvt>
 #include <cstdarg>
 #include <cstddef>
@@ -664,3 +665,21 @@ std::vector<std::string> CommandLineToUtf8Argv(const wchar_t* command_line)
   return argv;
 }
 #endif
+
+std::string GetEscapedHtml(std::string html)
+{
+  static constexpr std::array<std::array<const char*, 2>, 5> replacements{{
+      // Escape ampersand first to avoid escaping the ampersands in other replacements
+      {{"&", "&amp;"}},
+      {{"<", "&lt;"}},
+      {{">", "&gt;"}},
+      {{"\"", "&quot;"}},
+      {{"'", "&apos;"}},
+  }};
+
+  for (const auto& [unescaped, escaped] : replacements)
+  {
+    html = ReplaceAll(html, unescaped, escaped);
+  }
+  return html;
+}
diff --git a/Source/Core/Common/StringUtil.h b/Source/Core/Common/StringUtil.h
index ada0eee3bd..6b7bd14361 100644
--- a/Source/Core/Common/StringUtil.h
+++ b/Source/Core/Common/StringUtil.h
@@ -242,3 +242,5 @@ inline bool IsPrintableCharacter(char c)
 #ifdef _WIN32
 std::vector<std::string> CommandLineToUtf8Argv(const wchar_t* command_line);
 #endif
+
+std::string GetEscapedHtml(std::string html);
diff --git a/Source/Core/UICommon/AutoUpdate.cpp b/Source/Core/UICommon/AutoUpdate.cpp
index 5808d3ac2e..f5898f592b 100644
--- a/Source/Core/UICommon/AutoUpdate.cpp
+++ b/Source/Core/UICommon/AutoUpdate.cpp
@@ -109,10 +109,10 @@ std::string GenerateChangelog(const picojson::array& versions)
       {
         changelog += ver_obj["shortrev"].get<std::string>();
       }
-
+      const std::string escaped_description =
+          GetEscapedHtml(ver_obj["short_descr"].get<std::string>());
       changelog += " by <a href = \"" + ver_obj["author_url"].get<std::string>() + "\">" +
-                   ver_obj["author"].get<std::string>() + "</a> &mdash; " +
-                   ver_obj["short_descr"].get<std::string>();
+                   ver_obj["author"].get<std::string>() + "</a> &mdash; " + escaped_description;
     }
     else
     {
diff --git a/Source/UnitTests/Common/StringUtilTest.cpp b/Source/UnitTests/Common/StringUtilTest.cpp
index b9b186c131..fe837be455 100644
--- a/Source/UnitTests/Common/StringUtilTest.cpp
+++ b/Source/UnitTests/Common/StringUtilTest.cpp
@@ -105,3 +105,13 @@ TEST(StringUtil, ToString_TryParse_Roundtrip)
   DoRoundTripTest<float>({0.0f, 1.0f, -1.0f, -0.5f, 0.5f, -1e-3f, 1e-3f, 1e3f, -1e3f});
   DoRoundTripTest<double>({0.0, 1.0, -1.0, -0.5, 0.5, -1e-3, 1e-3, 1e3, -1e3});
 }
+
+TEST(StringUtil, GetEscapedHtml)
+{
+  static constexpr auto no_escape_needed =
+      "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+      "!@#$%^*()-_=+,./?;:[]{}| \\\t\n";
+  EXPECT_EQ(GetEscapedHtml(no_escape_needed), no_escape_needed);
+  EXPECT_EQ(GetEscapedHtml("&<>'\""), "&amp;&lt;&gt;&apos;&quot;");
+  EXPECT_EQ(GetEscapedHtml("&&&"), "&amp;&amp;&amp;");
+}