[PATCH] D109386: Fix use-after-free from GlobalCtors associated data

[Lei Wang via Phabricator via cfe-commits]

wlei created this revision.
Herald added subscribers: hoy, wenlei, lxfind.
wlei requested review of this revision.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D109386

Files:
  clang/lib/CodeGen/CodeGenModule.cpp
  clang/lib/CodeGen/CodeGenModule.h


Index: clang/lib/CodeGen/CodeGenModule.h
===================================================================
--- clang/lib/CodeGen/CodeGenModule.h
+++ clang/lib/CodeGen/CodeGenModule.h
@@ -1526,6 +1526,8 @@
   void EmitPointerToInitFunc(const VarDecl *VD, llvm::GlobalVariable *Addr,
                              llvm::Function *InitFunc, InitSegAttr *ISA);
 
+  void UpdateADOfGlobalCtors(llvm::Constant *Old, llvm::Constant *New);
+
   // FIXME: Hardcoding priority here is gross.
   void AddGlobalCtor(llvm::Function *Ctor, int Priority = 65535,
                      llvm::Constant *AssociatedData = nullptr);
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -1421,6 +1421,14 @@
   return getModule().getNamedValue(Name);
 }
 
+void CodeGenModule::UpdateADOfGlobalCtors(llvm::Constant *Old, llvm::Constant 
*New) {
+  for(auto &S : GlobalCtors) {
+    if(S.AssociatedData == Old) {
+      S.AssociatedData = New;
+    }
+  }
+}
+
 /// AddGlobalCtor - Add a function to the list that will be called before
 /// main() runs.
 void CodeGenModule::AddGlobalCtor(llvm::Function *Ctor, int Priority,
@@ -3901,6 +3909,8 @@
       llvm::Constant *NewPtrForOldDecl =
           llvm::ConstantExpr::getBitCast(GV, Entry->getType());
       Entry->replaceAllUsesWith(NewPtrForOldDecl);
+
+      UpdateADOfGlobalCtors(Entry, GV);
     }
 
     Entry->eraseFromParent();



Index: clang/lib/CodeGen/CodeGenModule.h
===================================================================
--- clang/lib/CodeGen/CodeGenModule.h
+++ clang/lib/CodeGen/CodeGenModule.h
@@ -1526,6 +1526,8 @@
   void EmitPointerToInitFunc(const VarDecl *VD, llvm::GlobalVariable *Addr,
                              llvm::Function *InitFunc, InitSegAttr *ISA);
 
+  void UpdateADOfGlobalCtors(llvm::Constant *Old, llvm::Constant *New);
+
   // FIXME: Hardcoding priority here is gross.
   void AddGlobalCtor(llvm::Function *Ctor, int Priority = 65535,
                      llvm::Constant *AssociatedData = nullptr);
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -1421,6 +1421,14 @@
   return getModule().getNamedValue(Name);
 }
 
+void CodeGenModule::UpdateADOfGlobalCtors(llvm::Constant *Old, llvm::Constant *New) {
+  for(auto &S : GlobalCtors) {
+    if(S.AssociatedData == Old) {
+      S.AssociatedData = New;
+    }
+  }
+}
+
 /// AddGlobalCtor - Add a function to the list that will be called before
 /// main() runs.
 void CodeGenModule::AddGlobalCtor(llvm::Function *Ctor, int Priority,
@@ -3901,6 +3909,8 @@
       llvm::Constant *NewPtrForOldDecl =
           llvm::ConstantExpr::getBitCast(GV, Entry->getType());
       Entry->replaceAllUsesWith(NewPtrForOldDecl);
+
+      UpdateADOfGlobalCtors(Entry, GV);
     }
 
     Entry->eraseFromParent();

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