From ef9208047dc8770f6263b483d7a442df703bc42b Mon Sep 17 00:00:00 2001
From: Andreas Kling <andreas@ladybird.org>
Date: Thu, 26 Sep 2024 07:42:49 +0200
Subject: [PATCH] LibJS: Don't infinite loop on unknown console.log formatting
 specifiers

---
 .../regress/console-log-bogus-formatting-specifier.txt     | 1 +
 .../regress/console-log-bogus-formatting-specifier.html    | 7 +++++++
 Userland/Libraries/LibJS/Console.cpp                       | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 Tests/LibWeb/Text/expected/regress/console-log-bogus-formatting-specifier.txt
 create mode 100644 Tests/LibWeb/Text/input/regress/console-log-bogus-formatting-specifier.html

diff --git a/Tests/LibWeb/Text/expected/regress/console-log-bogus-formatting-specifier.txt b/Tests/LibWeb/Text/expected/regress/console-log-bogus-formatting-specifier.txt
new file mode 100644
index 00000000000..23b535695b9
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/regress/console-log-bogus-formatting-specifier.txt
@@ -0,0 +1 @@
+PASS (didn't hang)
diff --git a/Tests/LibWeb/Text/input/regress/console-log-bogus-formatting-specifier.html b/Tests/LibWeb/Text/input/regress/console-log-bogus-formatting-specifier.html
new file mode 100644
index 00000000000..80a777c6377
--- /dev/null
+++ b/Tests/LibWeb/Text/input/regress/console-log-bogus-formatting-specifier.html
@@ -0,0 +1,7 @@
+<script src="../include.js"></script>
+<script>
+    test(() => {
+        console.log("%z%z", 1, 2);
+        println("PASS (didn't hang)");
+    });
+</script>
diff --git a/Userland/Libraries/LibJS/Console.cpp b/Userland/Libraries/LibJS/Console.cpp
index 3e3c9c184a5..1fb6f1d5347 100644
--- a/Userland/Libraries/LibJS/Console.cpp
+++ b/Userland/Libraries/LibJS/Console.cpp
@@ -818,7 +818,7 @@ ThrowCompletionOr<MarkedVector<Value>> ConsoleClient::formatter(MarkedVector<Val
     auto find_specifier = [](StringView target) -> Optional<StringView> {
         size_t start_index = 0;
         while (start_index < target.length()) {
-            auto maybe_index = target.find('%');
+            auto maybe_index = target.find('%', start_index);
             if (!maybe_index.has_value())
                 return {};