[clang] [clang] Fix crash when `__builtin_function_start` is given an invalid first parameter (PR #155506)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang

Author: Vincent (Mr-Anyone)

<details>
<summary>Changes</summary>

Prevent a crash in `__builtin_function_start` by adding a check for an invalid first parameter.

fixes #<!-- -->113323

---
Full diff: https://github.com/llvm/llvm-project/pull/155506.diff


3 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+2) 
- (modified) clang/lib/Sema/SemaChecking.cpp (+3) 
- (added) clang/test/SemaCXX/gh113323.cpp (+5) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 9a05eea9de8ac..9cd8a10b72c36 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -258,6 +258,8 @@ Bug Fixes in This Version
   targets that treat ``_Float16``/``__fp16`` as native scalar types. Previously
   the warning was silently lost because the operands differed only by an implicit
   cast chain. (#GH149967).
+- Fix crash in ``__builtin_function_start`` by checking for invalid
+  first parameter. (#GH113323).
 - Fixed a crash with incompatible pointer to integer conversions in designated
   initializers involving string literals. (#GH154046)
 - Clang now emits a frontend error when a function marked with the `flatten` attribute
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 6e777fb9aec8e..d137ccb95d295 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -286,6 +286,9 @@ static bool BuiltinFunctionStart(Sema &S, CallExpr *TheCall) {
   if (S.checkArgCount(TheCall, 1))
     return true;
 
+  if(TheCall->getArg(0)->containsErrors())
+      return true;
+
   ExprResult Arg = S.DefaultFunctionArrayLvalueConversion(TheCall->getArg(0));
   if (Arg.isInvalid())
     return true;
diff --git a/clang/test/SemaCXX/gh113323.cpp b/clang/test/SemaCXX/gh113323.cpp
new file mode 100644
index 0000000000000..c753407b6932b
--- /dev/null
+++ b/clang/test/SemaCXX/gh113323.cpp
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+int a() {} // expected-warning {{non-void function does not return a value}}
+constexpr void (*d)() = a; // expected-error {{cannot initialize a variable of type}}
+const void *f = __builtin_function_start(d);

``````````

</details>


https://github.com/llvm/llvm-project/pull/155506