Fix a use-after-free bug found by ASan. You can't assign a temporary

chandlerc · chandlerc · commit 0956ae5ac2d5 · 2012-12-08T03:10:14.000Z
std::string to a StringRef. Moreover, the method being called accepts a Twine to simplify these patterns. Fixes this ASan failure: ==6312== ERROR: AddressSanitizer: heap-use-after-free on address 0x7fd558b1af58 at pc 0xcb7529 bp 0x7fffff572080 sp 0x7fffff572078 READ of size 1 at 0x7fd558b1af58 thread T0 #0 0xcb7528 .../llvm/include/llvm/ADT/StringRef.h:192 llvm::StringRef::operator[]() #1 0x1d53c0a .../llvm/include/llvm/ADT/StringExtras.h:128 llvm::HashString() #2 0x1d53878 .../llvm/lib/Support/StringMap.cpp:64 llvm::StringMapImpl::LookupBucketFor() #3 0x1b6872f .../llvm/include/llvm/ADT/StringMap.h:352 llvm::StringMap<>::GetOrCreateValue<>() #4 0x1b61836 .../llvm/lib/MC/MCContext.cpp:109 llvm::MCContext::GetOrCreateSymbol() #5 0xe9fd47 .../llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp:154 (anonymous namespace)::ARMELFStreamer::EmitMappingSymbol() #6 0xea01dd .../llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp:133 (anonymous namespace)::ARMELFStreamer::EmitDataMappingSymbol() #7 0xe9f78b .../llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp:91 (anonymous namespace)::ARMELFStreamer::EmitBytes() #8 0x1b15d82 .../llvm/lib/MC/MCStreamer.cpp:89 llvm::MCStreamer::EmitIntValue() #9 0xcc0f9b .../llvm/lib/Target/ARM/ARMAsmPrinter.cpp:713 llvm::ARMAsmPrinter::emitAttributes() #10 0xcc0d44 .../llvm/lib/Target/ARM/ARMAsmPrinter.cpp:632 llvm::ARMAsmPrinter::EmitStartOfAsmFile() #11 0x14692ad .../llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:162 llvm::AsmPrinter::doInitialization() #12 0x1bc4677 .../llvm/lib/VMCore/PassManager.cpp:1561 llvm::FPPassManager::doInitialization() #13 0x1bc4990 .../llvm/lib/VMCore/PassManager.cpp:1595 llvm::MPPassManager::runOnModule() #14 0x1bc55e5 .../llvm/lib/VMCore/PassManager.cpp:1705 llvm::PassManagerImpl::run() #15 0x1bc5878 .../llvm/lib/VMCore/PassManager.cpp:1740 llvm::PassManager::run() #16 0xc3954d .../llvm/tools/llc/llc.cpp:378 compileModule() #17 0xc38001 .../llvm/tools/llc/llc.cpp:194 main #18 0x7fd557d6a11c __libc_start_main 0x7fd558b1af58 is located 24 bytes inside of 29-byte region [0x7fd558b1af40,0x7fd558b1af5d) freed by thread T0 here: #0 0xc337da .../llvm/projects/compiler-rt/lib/asan/asan_new_delete.cc:56 operator delete() #1 0x1ee9cef .../libstdc++-v3/include/bits/basic_string.h:535 std::string::~string() #2 0xea01dd .../llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp:133 (anonymous namespace)::ARMELFStreamer::EmitDataMappingSymbol() #3 0xe9f78b .../llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp:91 (anonymous namespace)::ARMELFStreamer::EmitBytes() #4 0x1b15d82 .../llvm/lib/MC/MCStreamer.cpp:89 llvm::MCStreamer::EmitIntValue() #5 0xcc0f9b .../llvm/lib/Target/ARM/ARMAsmPrinter.cpp:713 llvm::ARMAsmPrinter::emitAttributes() #6 0xcc0d44 .../llvm/lib/Target/ARM/ARMAsmPrinter.cpp:632 llvm::ARMAsmPrinter::EmitStartOfAsmFile() #7 0x14692ad .../llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp:162 llvm::AsmPrinter::doInitialization() #8 0x1bc4677 .../llvm/lib/VMCore/PassManager.cpp:1561 llvm::FPPassManager::doInitialization() #9 0x1bc4990 .../llvm/lib/VMCore/PassManager.cpp:1595 llvm::MPPassManager::runOnModule() #10 0x1bc55e5 .../llvm/lib/VMCore/PassManager.cpp:1705 llvm::PassManagerImpl::run() #11 0x1bc5878 .../llvm/lib/VMCore/PassManager.cpp:1740 llvm::PassManager::run() #12 0xc3954d .../llvm/tools/llc/llc.cpp:378 compileModule() #13 0xc38001 .../llvm/tools/llc/llc.cpp:194 main #14 0x7fd557d6a11c __libc_start_main git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169668 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp b/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp
@@ -150,8 +150,9 @@ class ARMELFStreamer : public MCELFStreamer {
     MCSymbol *Start = getContext().CreateTempSymbol();
     EmitLabel(Start);
 
-    StringRef UniqueName = Name.str() + "." + itostr(MappingSymbolCounter++);
-    MCSymbol *Symbol = getContext().GetOrCreateSymbol(UniqueName);
+    MCSymbol *Symbol =
+      getContext().GetOrCreateSymbol(Name.str() + "." +
+                                     itostr(MappingSymbolCounter++));
 
     MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
     MCELF::SetType(SD, ELF::STT_NOTYPE);
