[Clang] Prevent null pointer dereference in target attribute mangling

[smanna12]

This patch adds assertions in the getMangledNameImpl() function to ensure that the expected target attributes (TargetAttr, TargetVersionAttr, and TargetClonesAttr) are not null before they are passed to appendAttributeMangling() to prevent potential null pointer dereferences and improve the robustness of the attribute mangling process.

This assertion will trigger a runtime error with a clear message in debug build if any of the expected attributes are missing, facilitating early and easier diagnosis and debugging of such issues related to attribute mangling.

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-codegen

Author: None (smanna12)

Changes

This patch adds an assert in getMangledNameImpl() to ensure that the expected attributes (TargetAttr, TargetVersionAttr, and TargetClonesAttr) are checked for NULL value before being used by appendAttributeMangling().

---

Full diff: https://github.com/llvm/llvm-project/pull/94228.diff

1 Files Affected:

• (modified) clang/lib/CodeGen/CodeGenModule.cpp (+3)

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index c2314c3a57d33..7541817e41e86 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1853,18 +1853,21 @@ static std::string getMangledNameImpl(CodeGenModule &CGM, GlobalDecl GD,
         break;
       case MultiVersionKind::Target: {
         auto *Attr = FD->getAttr<TargetAttr>();
+        assert(Attr && "Expected TargetAttr to be present for attribute mangling");
         const ABIInfo &Info = CGM.getTargetCodeGenInfo().getABIInfo();
         Info.appendAttributeMangling(Attr, Out);
         break;
       }
       case MultiVersionKind::TargetVersion: {
         auto *Attr = FD->getAttr<TargetVersionAttr>();
+        assert(Attr && "Expected TargetVersionAttr to be present for attribute mangling");
         const ABIInfo &Info = CGM.getTargetCodeGenInfo().getABIInfo();
         Info.appendAttributeMangling(Attr, Out);
         break;
       }
       case MultiVersionKind::TargetClones: {
         auto *Attr = FD->getAttr<TargetClonesAttr>();
+        assert(Attr && "Expected TargetClonesAttr to be present for attribute mangling");
         unsigned Index = GD.getMultiVersionIndex();
         const ABIInfo &Info = CGM.getTargetCodeGenInfo().getABIInfo();
         Info.appendAttributeMangling(Attr, Index, Out);

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[smanna12]

Thank you @efriedma-quic for reviews!