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Change-Id: I5c9cf7ee1474ebb9d0c0bf89830eaee852ce2f8b
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**Mitigation for:** google/sanitizers#749 **Disclosure:** I'm not an ASan compiler expert yet (I'm trying to learn!), I primarily work in the runtime. Some of this PR was developed with the help of AI tools (primarily as a "fuzzy `grep` engine"), but I've manually refined and tested the output, and can speak for every line. In general, I used it only to orient myself and for "rubberducking". **Context:** The msvc ASan team (👋 ) has received an internal request to improve clang's exception handling under ASan for Windows. Namely, we're interested in **mitigating** this bug: google/sanitizers#749 To summarize, today, clang + ASan produces a false-positive error for this program: ```C++ #include <cstdio> #include <exception> int main() { try { throw std::exception("test"); }catch (const std::exception& ex){ puts(ex.what()); } return 0; } ``` The error reads as such: ``` C:\Users\dajusto\source\repros\upstream>type main.cpp #include <cstdio> #include <exception> int main() { try { throw std::exception("test"); }catch (const std::exception& ex){ puts(ex.what()); } return 0; } C:\Users\dajusto\source\repros\upstream>"C:\Users\dajusto\source\repos\llvm-project\build.runtimes\bin\clang.exe" -fsanitize=address -g -O0 main.cpp C:\Users\dajusto\source\repros\upstream>a.exe ================================================================= ==19112==ERROR: AddressSanitizer: access-violation on unknown address 0x000000000000 (pc 0x7ff72c7c11d9 bp 0x0080000ff960 sp 0x0080000fcf50 T0) ==19112==The signal is caused by a READ memory access. ==19112==Hint: address points to the zero page. #0 0x7ff72c7c11d8 in main C:\Users\dajusto\source\repros\upstream\main.cpp:8 #1 0x7ff72c7d479f in _CallSettingFrame C:\repos\msvc\src\vctools\crt\vcruntime\src\eh\amd64\handlers.asm:49 #2 0x7ff72c7c8944 in __FrameHandler3::CxxCallCatchBlock(struct _EXCEPTION_RECORD *) C:\repos\msvc\src\vctools\crt\vcruntime\src\eh\frame.cpp:1567 #3 0x7ffb4a90e3e5 (C:\WINDOWS\SYSTEM32\ntdll.dll+0x18012e3e5) #4 0x7ff72c7c1128 in main C:\Users\dajusto\source\repros\upstream\main.cpp:6 #5 0x7ff72c7c33db in invoke_main C:\repos\msvc\src\vctools\crt\vcstartup\src\startup\exe_common.inl:78 #6 0x7ff72c7c33db in __scrt_common_main_seh C:\repos\msvc\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288 #7 0x7ffb49b05c06 (C:\WINDOWS\System32\KERNEL32.DLL+0x180035c06) #8 0x7ffb4a8455ef (C:\WINDOWS\SYSTEM32\ntdll.dll+0x1800655ef) ==19112==Register values: rax = 0 rbx = 80000ff8e0 rcx = 27d76d00000 rdx = 80000ff8e0 rdi = 80000fdd50 rsi = 80000ff6a0 rbp = 80000ff960 rsp = 80000fcf50 r8 = 100 r9 = 19930520 r10 = 8000503a90 r11 = 80000fd540 r12 = 80000fd020 r13 = 0 r14 = 80000fdeb8 r15 = 0 AddressSanitizer can not provide additional info. SUMMARY: AddressSanitizer: access-violation C:\Users\dajusto\source\repros\upstream\main.cpp:8 in main ==19112==ABORTING ``` The root of the issue _appears to be_ that ASan's instrumentation is incompatible with Window's assumptions for instantiating `catch`-block's parameters (`ex` in the snippet above). The nitty gritty details are lost on me, but I understand that to make this work without loss of ASan coverage, a "serious" refactoring is needed. In the meantime, users risk false positive errors when pairing ASan + catch-block parameters on Windows. **To mitigate this** I think we should avoid instrumenting catch-block parameters on Windows. It appears to me this is as "simple" as marking catch block parameters as "uninteresting" in `AddressSanitizer::isInterestingAlloca`. My manual tests seem to confirm this. I believe this is strictly better than today's status quo, where the runtime generates false positives. Although we're now explicitly choosing to instrument less, the benefit is that now more programs can run with ASan without _funky_ macros that disable ASan on exception blocks. **This PR:** implements the mitigation above, and creates a simple new test for it. _Thanks!_ --------- Co-authored-by: Antonio Frighetto <[email protected]>
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…am (llvm#167724) This got exposed by `09262656f32ab3f2e1d82e5342ba37eecac52522`. The underlying stream of `m_os` is referenced by the `TextDiagnostic` member of `TextDiagnosticPrinter`. It got turned into a `llvm::formatted_raw_ostream` in the commit above. When `~TextDiagnosticPrinter` (and thus `~TextDiagnostic`) is invoked, we now call `~formatted_raw_ostream`, which tries to access the underlying stream. But `m_os` was already deleted because it is earlier in the order of destruction in `TextDiagnosticPrinter`. Move the `m_os` member before the `TextDiagnosticPrinter` to avoid a use-after-free. Drive-by: * Also move the `m_output` member which the `m_os` holds a reference to. The fact it's a reference indicates the expectation is most likely that the string outlives the stream. The ASAN macOS bot is currently failing with this: ``` 08:15:39 ================================================================= 08:15:39 ==61103==ERROR: AddressSanitizer: heap-use-after-free on address 0x60600012cf40 at pc 0x00012140d304 bp 0x00016eecc850 sp 0x00016eecc848 08:15:39 READ of size 8 at 0x60600012cf40 thread T0 08:15:39 #0 0x00012140d300 in llvm::formatted_raw_ostream::releaseStream() FormattedStream.h:205 08:15:39 #1 0x00012140d3a4 in llvm::formatted_raw_ostream::~formatted_raw_ostream() FormattedStream.h:145 08:15:39 #2 0x00012604abf8 in clang::TextDiagnostic::~TextDiagnostic() TextDiagnostic.cpp:721 08:15:39 #3 0x00012605dc80 in clang::TextDiagnosticPrinter::~TextDiagnosticPrinter() TextDiagnosticPrinter.cpp:30 08:15:39 #4 0x00012605dd5c in clang::TextDiagnosticPrinter::~TextDiagnosticPrinter() TextDiagnosticPrinter.cpp:27 08:15:39 #5 0x0001231fb210 in (anonymous namespace)::StoringDiagnosticConsumer::~StoringDiagnosticConsumer() ClangModulesDeclVendor.cpp:47 08:15:39 #6 0x0001231fb3bc in (anonymous namespace)::StoringDiagnosticConsumer::~StoringDiagnosticConsumer() ClangModulesDeclVendor.cpp:47 08:15:39 #7 0x000129aa9d70 in clang::DiagnosticsEngine::~DiagnosticsEngine() Diagnostic.cpp:91 08:15:39 #8 0x0001230436b8 in llvm::RefCountedBase<clang::DiagnosticsEngine>::Release() const IntrusiveRefCntPtr.h:103 08:15:39 ROCm#9 0x0001231fe6c8 in (anonymous namespace)::ClangModulesDeclVendorImpl::~ClangModulesDeclVendorImpl() ClangModulesDeclVendor.cpp:93 08:15:39 ROCm#10 0x0001231fe858 in (anonymous namespace)::ClangModulesDeclVendorImpl::~ClangModulesDeclVendorImpl() ClangModulesDeclVendor.cpp:93 ... 08:15:39 08:15:39 0x60600012cf40 is located 32 bytes inside of 56-byte region [0x60600012cf20,0x60600012cf58) 08:15:39 freed by thread T0 here: 08:15:39 #0 0x0001018abb88 in _ZdlPv+0x74 (libclang_rt.asan_osx_dynamic.dylib:arm64e+0x4bb88) 08:15:39 #1 0x0001231fb1c0 in (anonymous namespace)::StoringDiagnosticConsumer::~StoringDiagnosticConsumer() ClangModulesDeclVendor.cpp:47 08:15:39 #2 0x0001231fb3bc in (anonymous namespace)::StoringDiagnosticConsumer::~StoringDiagnosticConsumer() ClangModulesDeclVendor.cpp:47 08:15:39 #3 0x000129aa9d70 in clang::DiagnosticsEngine::~DiagnosticsEngine() Diagnostic.cpp:91 08:15:39 #4 0x0001230436b8 in llvm::RefCountedBase<clang::DiagnosticsEngine>::Release() const IntrusiveRefCntPtr.h:103 08:15:39 #5 0x0001231fe6c8 in (anonymous namespace)::ClangModulesDeclVendorImpl::~ClangModulesDeclVendorImpl() ClangModulesDeclVendor.cpp:93 08:15:39 #6 0x0001231fe858 in (anonymous namespace)::ClangModulesDeclVendorImpl::~ClangModulesDeclVendorImpl() ClangModulesDeclVendor.cpp:93 ... 08:15:39 08:15:39 previously allocated by thread T0 here: 08:15:39 #0 0x0001018ab760 in _Znwm+0x74 (libclang_rt.asan_osx_dynamic.dylib:arm64e+0x4b760) 08:15:39 #1 0x0001231f8dec in lldb_private::ClangModulesDeclVendor::Create(lldb_private::Target&) ClangModulesDeclVendor.cpp:732 08:15:39 #2 0x00012320af58 in lldb_private::ClangPersistentVariables::GetClangModulesDeclVendor() ClangPersistentVariables.cpp:124 08:15:39 #3 0x0001232111f0 in lldb_private::ClangUserExpression::PrepareForParsing(lldb_private::DiagnosticManager&, lldb_private::ExecutionContext&, bool) ClangUserExpression.cpp:536 08:15:39 #4 0x000123213790 in lldb_private::ClangUserExpression::Parse(lldb_private::DiagnosticManager&, lldb_private::ExecutionContext&, lldb_private::ExecutionPolicy, bool, bool) ClangUserExpression.cpp:647 08:15:39 #5 0x00012032b258 in lldb_private::UserExpression::Evaluate(lldb_private::ExecutionContext&, lldb_private::EvaluateExpressionOptions const&, llvm::StringRef, llvm::StringRef, std::__1::shared_ptr<lldb_private::ValueObject>&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>*, lldb_private::ValueObject*) UserExpression.cpp:280 08:15:39 #6 0x000120724010 in lldb_private::Target::EvaluateExpression(llvm::StringRef, lldb_private::ExecutionContextScope*, std::__1::shared_ptr<lldb_private::ValueObject>&, lldb_private::EvaluateExpressionOptions const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>*, lldb_private::ValueObject*) Target.cpp:2905 08:15:39 #7 0x00011fc7bde0 in lldb::SBTarget::EvaluateExpression(char const*, lldb::SBExpressionOptions const&) SBTarget.cpp:2305 08:15:39 ==61103==ABORTING ... ```
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Change-Id: I5c9cf7ee1474ebb9d0c0bf89830eaee852ce2f8b