[PATCH] D44000: [clang] Fix use-after-free on code completion

[Ilya Biryukov via Phabricator via cfe-commits]

ilya-biryukov created this revision.
ilya-biryukov added a reviewer: sammccall.
Herald added subscribers: ioeric, jkorous-apple, klimek.

Found by asan. Fiddling with code completion AST after
FrontendAction::Exceute can lead to errors.
Calling the callback in ProcessCodeCompleteResults to make sure we
don't access uninitialized state.

This particular issue comes from the fact that Sema::TUScope is
deleted when destructor of ~Parser runs, but still present in
Sema::TUScope and accessed when building completion items.

I'm still struggling to come up with a small repro. The relevant
stackframes reported by asan are:
ERROR: AddressSanitizer: heap-use-after-free on address
READ of size 8 at 0x61400020d090 thread T175

  #0 0x5632dff7821b in llvm::SmallPtrSetImplBase::isSmall() const include/llvm/ADT/SmallPtrSet.h:195:33
  #1 0x5632e0335901 in llvm::SmallPtrSetImplBase::insert_imp(void const*) include/llvm/ADT/SmallPtrSet.h:127:9
  #2 0x5632e067347d in llvm::SmallPtrSetImpl<clang::Decl*>::insert(clang::Decl*) include/llvm/ADT/SmallPtrSet.h:372:14
  #3 0x5632e065df80 in clang::Scope::AddDecl(clang::Decl*) tools/clang/include/clang/Sema/Scope.h:287:18
  #4 0x5632e0623eea in clang::ASTReader::pushExternalDeclIntoScope(clang::NamedDecl*, clang::DeclarationName) clang/lib/Serialization/ASTReader.cpp
  #5 0x5632e062ce74 in clang::ASTReader::finishPendingActions() tools/clang/lib/Serialization/ASTReader.cpp:9164:9
  ....
  #30 0x5632e02009c4 in clang::index::generateUSRForDecl(clang::Decl const*, llvm::SmallVectorImpl<char>&) tools/clang/lib/Index/USRGeneration.cpp:1037:6
  #31 0x5632dff73eab in clang::clangd::(anonymous namespace)::getSymbolID(clang::CodeCompletionResult const&) tools/clang/tools/extra/clangd/CodeComplete.cpp:326:20
  #32 0x5632dff6fe91 in clang::clangd::CodeCompleteFlow::mergeResults(std::vector<clang::CodeCompletionResult, std::allocator<clang::CodeCompletionResult> > const&, clang::clangd::SymbolSlab const&)::'lambda'(clang::CodeCompletionResult const&)::operator()(clang::CodeCompletionResult const&) tools/clang/tools/extra/clangd/CodeComplete.cpp:938:24
  #33 0x5632dff6e426 in clang::clangd::CodeCompleteFlow::mergeResults(std::vector<clang::CodeCompletionResult, std::allocator<clang::CodeCompletionResult> > const&, clang::clangd::SymbolSlab const&) third_party/llvm/llvm/tools/clang/tools/extra/clangd/CodeComplete.cpp:949:38
  #34 0x5632dff7a34d in clang::clangd::CodeCompleteFlow::runWithSema() llvm/tools/clang/tools/extra/clangd/CodeComplete.cpp:894:16
  #35 0x5632dff6df6a in clang::clangd::CodeCompleteFlow::run(clang::clangd::(anonymous namespace)::SemaCompleteInput const&) &&::'lambda'()::operator()() const third_party/llvm/llvm/tools/clang/tools/extra/clangd/CodeComplete.cpp:858:35
  #36 0x5632dff6cd42 in clang::clangd::(anonymous namespace)::semaCodeComplete(std::unique_ptr<clang::CodeCompleteConsumer, std::default_delete<clang::CodeCompleteConsumer> >, clang::CodeCompleteOptions const&, clang::clangd::(anonymous namespace)::SemaCompleteInput const&, llvm::function_ref<void ()>) tools/clang/tools/extra/clangd/CodeComplete.cpp:735:5

0x61400020d090 is located 80 bytes inside of 432-byte region [0x61400020d040,0x61400020d1f0)
freed by thread T175  here:

  #0 0x5632df74e115 in operator delete(void*, unsigned long) projects/compiler-rt/lib/asan/asan_new_delete.cc:161:3
  #1 0x5632e0b06973 in clang::Parser::~Parser() tools/clang/lib/Parse/Parser.cpp:410:3
  #2 0x5632e0b06ddd in clang::Parser::~Parser() clang/lib/Parse/Parser.cpp:408:19
  #3 0x5632e0b03286 in std::unique_ptr<clang::Parser, std::default_delete<clang::Parser> >::~unique_ptr() .../bits/unique_ptr.h:236:4
  #4 0x5632e0b021c4 in clang::ParseAST(clang::Sema&, bool, bool) tools/clang/lib/Parse/ParseAST.cpp:182:1
  #5 0x5632e0726544 in clang::FrontendAction::Execute() tools/clang/lib/Frontend/FrontendAction.cpp:904:8
  #6 0x5632dff6cd05 in clang::clangd::(anonymous namespace)::semaCodeComplete(std::unique_ptr<clang::CodeCompleteConsumer, std::default_delete<clang::CodeCompleteConsumer> >, clang::CodeCompleteOptions const&, clang::clangd::(anonymous namespace)::SemaCompleteInput const&, llvm::function_ref<void ()>) tools/clang/tools/extra/clangd/CodeComplete.cpp:728:15


Repository:
  rCTE Clang Tools Extra

https://reviews.llvm.org/D44000

Files:
  clangd/CodeComplete.cpp

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