[llvm] Add clang::lifetimebound annotation to StringRef constructors. (PR #113878)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-adt

Author: Haojian Wu (hokein)

<details>
<summary>Changes</summary>

Adding the lifetimebound annotation to the ArrayRef's array constructor can enable us to detect the following use-after-free issues:

```
llvm::StringRef TestZoneName() {
   char test[] = "foo"; // oops, missing static
   return test; // use-after-free.
}
```

See #<!-- -->113533

---
Full diff: https://github.com/llvm/llvm-project/pull/113878.diff


1 Files Affected:

- (modified) llvm/include/llvm/ADT/StringRef.h (+3-2) 


``````````diff
diff --git a/llvm/include/llvm/ADT/StringRef.h b/llvm/include/llvm/ADT/StringRef.h
index f879bbf7164fd6..0dcd4d90086eff 100644
--- a/llvm/include/llvm/ADT/StringRef.h
+++ b/llvm/include/llvm/ADT/StringRef.h
@@ -81,7 +81,7 @@ namespace llvm {
     StringRef(std::nullptr_t) = delete;
 
     /// Construct a string ref from a cstring.
-    /*implicit*/ constexpr StringRef(const char *Str)
+    /*implicit*/ constexpr StringRef(const char *Str LLVM_LIFETIME_BOUND)
         : View(Str, Str ?
     // GCC 7 doesn't have constexpr char_traits. Fall back to __builtin_strlen.
 #if defined(_GLIBCXX_RELEASE) && _GLIBCXX_RELEASE < 8
@@ -93,7 +93,8 @@ namespace llvm {
     }
 
     /// Construct a string ref from a pointer and length.
-    /*implicit*/ constexpr StringRef(const char *data, size_t length)
+    /*implicit*/ constexpr StringRef(const char *data LLVM_LIFETIME_BOUND,
+                                     size_t length)
         : View(data, length) {}
 
     /// Construct a string ref from an std::string.

``````````

</details>


https://github.com/llvm/llvm-project/pull/113878