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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/265493">265493</a></dd>
<dt>Author</dt> <dd>mark.lam@apple.com</dd>
<dt>Date</dt> <dd>2020-08-11 01:23:16 -0700 (Tue, 11 Aug 2020)</dd>
</dl>

<h3>Log Message</h3>
<pre>ScriptExecutable::newCodeBlockFor() neglected to set the exception pointer result in one case.
https://bugs.webkit.org/show_bug.cgi?id=215357
<rdar://problem/57675112>

Reviewed by Yusuke Suzuki.

At the bottom of ScriptExecutable::newCodeBlockFor(), it calls:
    RELEASE_AND_RETURN(throwScope, FunctionCodeBlock::create(vm, executable, unlinkedCodeBlock, scope));

However, ScriptExecutable::newCodeBlockFor() has 2 return values: a CodeBlock*,
and a passed in Exception*& that needs to be set if there's an exception.
FunctionCodeBlock::create() is capable of returning a null CodeBlock* because
CodeBlock::finishCreation() can throw exceptions.  As a result, we have a scenario
here where ScriptExecutable::newCodeBlockFor() can return a null CodeBlock* without
setting the Exception*& result.

Consequently, Interpreter::executeCall() is relying on this and can end up
crashing while dereferencing a null CodeBlock* because the exception result was
not set.

This patch fixes ScriptExecutable::newCodeBlockFor() to set the exception result.

* runtime/ScriptExecutable.cpp:
(JSC::ScriptExecutable::newCodeBlockFor):</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreruntimeScriptExecutablecpp">trunk/Source/JavaScriptCore/runtime/ScriptExecutable.cpp</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (265492 => 265493)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog    2020-08-11 08:17:37 UTC (rev 265492)
+++ trunk/Source/JavaScriptCore/ChangeLog       2020-08-11 08:23:16 UTC (rev 265493)
</span><span class="lines">@@ -1,3 +1,30 @@
</span><ins>+2020-08-11  Mark Lam  <mark.lam@apple.com>
+
+        ScriptExecutable::newCodeBlockFor() neglected to set the exception pointer result in one case.
+        https://bugs.webkit.org/show_bug.cgi?id=215357
+        <rdar://problem/57675112>
+
+        Reviewed by Yusuke Suzuki.
+
+        At the bottom of ScriptExecutable::newCodeBlockFor(), it calls:
+            RELEASE_AND_RETURN(throwScope, FunctionCodeBlock::create(vm, executable, unlinkedCodeBlock, scope));
+
+        However, ScriptExecutable::newCodeBlockFor() has 2 return values: a CodeBlock*,
+        and a passed in Exception*& that needs to be set if there's an exception.
+        FunctionCodeBlock::create() is capable of returning a null CodeBlock* because
+        CodeBlock::finishCreation() can throw exceptions.  As a result, we have a scenario
+        here where ScriptExecutable::newCodeBlockFor() can return a null CodeBlock* without
+        setting the Exception*& result.
+
+        Consequently, Interpreter::executeCall() is relying on this and can end up
+        crashing while dereferencing a null CodeBlock* because the exception result was
+        not set.
+
+        This patch fixes ScriptExecutable::newCodeBlockFor() to set the exception result.
+
+        * runtime/ScriptExecutable.cpp:
+        (JSC::ScriptExecutable::newCodeBlockFor):
+
</ins><span class="cx"> 2020-08-10  Lauro Moura  <lmoura@igalia.com>
</span><span class="cx"> 
</span><span class="cx">         [CMake][JSC] Fix testapiScripts copy location
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreruntimeScriptExecutablecpp"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/runtime/ScriptExecutable.cpp (265492 => 265493)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/runtime/ScriptExecutable.cpp 2020-08-11 08:17:37 UTC (rev 265492)
+++ trunk/Source/JavaScriptCore/runtime/ScriptExecutable.cpp    2020-08-11 08:23:16 UTC (rev 265493)
</span><span class="lines">@@ -261,7 +261,7 @@
</span><span class="cx">         RELEASE_ASSERT(kind == CodeForCall);
</span><span class="cx">         RELEASE_ASSERT(!executable->m_evalCodeBlock);
</span><span class="cx">         RELEASE_ASSERT(!function);
</span><del>-        auto codeBlock = EvalCodeBlock::create(vm,
</del><ins>+        auto* codeBlock = EvalCodeBlock::create(vm,
</ins><span class="cx">             executable, executable->m_unlinkedEvalCodeBlock.get(), scope);
</span><span class="cx">         EXCEPTION_ASSERT(throwScope.exception() || codeBlock);
</span><span class="cx">         if (!codeBlock) {
</span><span class="lines">@@ -278,7 +278,7 @@
</span><span class="cx">         RELEASE_ASSERT(kind == CodeForCall);
</span><span class="cx">         RELEASE_ASSERT(!executable->m_programCodeBlock);
</span><span class="cx">         RELEASE_ASSERT(!function);
</span><del>-        auto codeBlock = ProgramCodeBlock::create(vm,
</del><ins>+        auto* codeBlock = ProgramCodeBlock::create(vm,
</ins><span class="cx">             executable, executable->m_unlinkedProgramCodeBlock.get(), scope);
</span><span class="cx">         EXCEPTION_ASSERT(throwScope.exception() || codeBlock);
</span><span class="cx">         if (!codeBlock) {
</span><span class="lines">@@ -295,7 +295,7 @@
</span><span class="cx">         RELEASE_ASSERT(kind == CodeForCall);
</span><span class="cx">         RELEASE_ASSERT(!executable->m_moduleProgramCodeBlock);
</span><span class="cx">         RELEASE_ASSERT(!function);
</span><del>-        auto codeBlock = ModuleProgramCodeBlock::create(vm,
</del><ins>+        auto* codeBlock = ModuleProgramCodeBlock::create(vm,
</ins><span class="cx">             executable, executable->m_unlinkedModuleProgramCodeBlock.get(), scope);
</span><span class="cx">         EXCEPTION_ASSERT(throwScope.exception() || codeBlock);
</span><span class="cx">         if (!codeBlock) {
</span><span class="lines">@@ -337,7 +337,10 @@
</span><span class="cx">         return nullptr;
</span><span class="cx">     }
</span><span class="cx"> 
</span><del>-    RELEASE_AND_RETURN(throwScope, FunctionCodeBlock::create(vm, executable, unlinkedCodeBlock, scope));
</del><ins>+    auto* codeBlock = FunctionCodeBlock::create(vm, executable, unlinkedCodeBlock, scope);
+    if (throwScope.exception())
+        exception = throwScope.exception();
+    return codeBlock;
</ins><span class="cx"> }
</span><span class="cx"> 
</span><span class="cx"> CodeBlock* ScriptExecutable::newReplacementCodeBlockFor(
</span></span></pre>
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