From 093f1dd805f699801079f55d0d490d80b463ccbb Mon Sep 17 00:00:00 2001
From: Andreas Kling <andreas@ladybird.org>
Date: Fri, 19 Jul 2024 14:57:23 +0200
Subject: [PATCH] LibWeb: Propagate exceptions from setAttribute() in
 DOMStringMap setter

We were incorrectly assuming that setAttribute() could never fail here,
even when passed an invalid name.

Found by Domato.
---
 .../DOM/DOMStringMap-setter-with-invalid-name.txt    |  1 +
 .../DOM/DOMStringMap-setter-with-invalid-name.html   | 12 ++++++++++++
 Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp      |  2 +-
 3 files changed, 14 insertions(+), 1 deletion(-)
 create mode 100644 Tests/LibWeb/Text/expected/DOM/DOMStringMap-setter-with-invalid-name.txt
 create mode 100644 Tests/LibWeb/Text/input/DOM/DOMStringMap-setter-with-invalid-name.html

diff --git a/Tests/LibWeb/Text/expected/DOM/DOMStringMap-setter-with-invalid-name.txt b/Tests/LibWeb/Text/expected/DOM/DOMStringMap-setter-with-invalid-name.txt
new file mode 100644
index 00000000000..05600d9cef4
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/DOM/DOMStringMap-setter-with-invalid-name.txt
@@ -0,0 +1 @@
+Setting DOMStringMap with an invalid name key throws? true
diff --git a/Tests/LibWeb/Text/input/DOM/DOMStringMap-setter-with-invalid-name.html b/Tests/LibWeb/Text/input/DOM/DOMStringMap-setter-with-invalid-name.html
new file mode 100644
index 00000000000..f5bd116db20
--- /dev/null
+++ b/Tests/LibWeb/Text/input/DOM/DOMStringMap-setter-with-invalid-name.html
@@ -0,0 +1,12 @@
+<script src="../include.js"></script>
+<script>
+    test(() => {
+        let threw = false;
+        try {
+            document.body.dataset["'\uDBF8"] = "foo";
+        } catch {
+            threw = true;
+        }
+        println("Setting DOMStringMap with an invalid name key throws? " + threw);
+    });
+</script>
diff --git a/Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp b/Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp
index cea0e51cbc5..1c7532860d5 100644
--- a/Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp
+++ b/Userland/Libraries/LibWeb/HTML/DOMStringMap.cpp
@@ -165,7 +165,7 @@ WebIDL::ExceptionOr<void> DOMStringMap::set_value_of_new_named_property(String c
     // FIXME: 4. If name does not match the XML Name production, throw an "InvalidCharacterError" DOMException.
 
     // 5. Set an attribute value for the DOMStringMap's associated element using name and value.
-    MUST(m_associated_element->set_attribute(data_name, value));
+    TRY(m_associated_element->set_attribute(data_name, value));
 
     return {};
 }