[PATCH] Fix clang-tidy delete of stack object

Aaron Wishnick aaron.s.wishnick at gmail.com
Wed Nov 12 12:32:54 PST 2014 

Understanding the bug better, I've attached a patch that more correctly
fixes this bug, by teaching ChainedDiagnosticConsumer how to not take
ownership of one of its arguments, and having SetupSerializedDiagnostics()
use it. Is there a more idiomatic way, in the LLVM project, of a "maybe"
owning pointer? I see that some related functions take a "ShouldOwnClient"
argument, but this seems a little more kludgy for two arguments with
separate ownership.

Thanks,
Aaron

On Wed, Nov 12, 2014 at 3:14 PM, Aaron Wishnick <aaron.s.wishnick at gmail.com>
wrote:

> Hi Alexander, sorry to dig up an old issue, but I've just gotten some more
> time to look into it. This is still reproducing for me on trunk, and I can
> see where the ChainedDiagnosticConsumer is created, as well as why it ends
> up trying to free a stack object. In short, there's a function
> SetupSerializedDiagnostics() in CompilerInstance.cpp that doesn't know how
> to handle the case where its DiagnosticsEngine doesn't own its client. This
> bug can be reproduced by using clang-tidy with a compilation database that
> uses the "--serialize-diagnostics" flag.
>
> When I run a debug build with the arguments "clang-tidy -p
> /path/to/compile_commands.json /path/to/source.cpp", I get a failed assert
> in tools/clang/lib/Frontend/CompilerInstance.cpp, line 173, in
> SetupSerializedDiagnostics():
>
> static void SetupSerializedDiagnostics(DiagnosticOptions *DiagOpts,
>                                        DiagnosticsEngine &Diags,
>                                        StringRef OutputFile) {
>   auto SerializedConsumer =
>       clang::serialized_diags::create(OutputFile, DiagOpts);
>
>   assert(Diags.ownsClient());
>   Diags.setClient(new ChainedDiagnosticConsumer(
>       std::unique_ptr<DiagnosticConsumer>(Diags.takeClient()),
>       std::move(SerializedConsumer)));
> }
>
> Stepping one stack frame up into createDiagnostics(), it looks like this
> code path is hit because the "if
> (!Opts->DiagnosticSerializationFile.empty())" condition on line 209 of
> CompilerInstance.cpp is met.
>
> If I skip that assert, and continue, I get that same "pointer being freed
> was not allocated" error, once the program finishes and the
> ChainedDiagnosticConsumer is deleted. The address is from the stack, rather
> than the heap, and it corresponds to the value of "Diags.Client" before
> that call to "Diags.takeClient()." In other words, I think the problem is
> that the DiagnosticsEngine passed into SetupSerializedDiagnostics doesn't
> own its client, and the client is stack allocated, and then the client is
> stored in a unique_ptr which is owned by the ChainedDiagnosticConsumer.
>
> Ultimately, I can see this comes from ClangTidy.cpp, line 470. This
> ClangTidyDiagnosticConsumer is created on the stack, and is the one that
> eventually ends up being freed, causing the bug.
>
> I am using this in conjunction with Xcode: I am using xcodebuild to build
> my project, and then oclint-xcodebuild to generate the
> compile_commands.json database. Sure enough, all of the commands in the
> compilation database include the argument "--serialize-diagnostics
> /path/to/source.dia". If I remove these arguments, this bug doesn't occur.
> So, I think the issue is that SetupSerializedDiagnostics doesn't know how
> to handle the case where the DiagnosticsEngine doesn't own its client.
>
> Hope this helps!
>
> Best,
> Aaron
>
>
> On Mon, Jun 23, 2014 at 9:51 AM, Alexander Kornienko <alexfh at google.com>
> wrote:
>
>>
>> On Mon, Jun 23, 2014 at 2:51 PM, Alexander Kornienko <alexfh at google.com>
>> wrote:
>>
>>>
>>> On Thu, Jun 19, 2014 at 5:59 PM, Aaron Wishnick <
>>> aaron.s.wishnick at gmail.com> wrote:
>>>
>>>> When I run clang-tidy on OS X 10.9.3, I immediately get this output:
>>>>
>>>> clang-tidy(97903,0x7fff782fb310) malloc: *** error for object
>>>> 0x7fff5fbfecd0: pointer being freed was not allocated
>>>> *** set a breakpoint in malloc_error_break to debug
>>>>
>>>> This occurs inside the destructor of ClangTidyDiagnosticConsumer.
>>>> Here's my callstack:
>>>>
>>>> #4 0x000000010058e3e2 in ~ClangTidyDiagnosticConsumer at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/tools/extra/clang-tidy/ClangTidyDiagnosticConsumer.h:190
>>>> #5 0x0000000100656a73 in
>>>> std::__1::default_delete<clang::DiagnosticConsumer>::operator()(clang::DiagnosticConsumer*)
>>>> const [inlined] at
>>>> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:2426
>>>> #6 0x0000000100656a4b in
>>>> std::__1::unique_ptr<clang::DiagnosticConsumer,
>>>> std::__1::default_delete<clang::DiagnosticConsumer>
>>>> >::reset(clang::DiagnosticConsumer*) [inlined] at
>>>> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:2625
>>>> #7 0x00000001006569f5 in ~unique_ptr [inlined] at
>>>> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:2593
>>>> #8 0x00000001006569f5 in ~unique_ptr [inlined] at
>>>> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:2593
>>>> #9 0x00000001006569f5 in ~ChainedDiagnosticConsumer at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/include/clang/Frontend/ChainedDiagnosticConsumer.h:23
>>>> #10 0x0000000100656595 in ~ChainedDiagnosticConsumer at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/include/clang/Frontend/ChainedDiagnosticConsumer.h:23
>>>> #11 0x00000001006565b9 in ~ChainedDiagnosticConsumer at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/include/clang/Frontend/ChainedDiagnosticConsumer.h:23
>>>> #12 0x00000001015eec84 in ~DiagnosticsEngine at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Basic/Diagnostic.cpp:68
>>>> #13 0x00000001015eec35 in ~DiagnosticsEngine at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Basic/Diagnostic.cpp:66
>>>> #14 0x00000001006bd3d3 in
>>>> llvm::RefCountedBase<clang::DiagnosticsEngine>::Release() const at
>>>> /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:55
>>>> #15 0x00000001006bd325 in
>>>> llvm::IntrusiveRefCntPtrInfo<clang::DiagnosticsEngine>::release(clang::DiagnosticsEngine*)
>>>> at /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:90
>>>> #16 0x00000001006bd2fd in
>>>> llvm::IntrusiveRefCntPtr<clang::DiagnosticsEngine>::release() at
>>>> /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:199
>>>> #17 0x00000001006bd2c5 in ~IntrusiveRefCntPtr at
>>>> /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:172
>>>> #18 0x00000001006bbe15 in ~IntrusiveRefCntPtr at
>>>> /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:172
>>>> #19 0x000000010065cbc1 in ~CompilerInstance at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Frontend/CompilerInstance.cpp:63
>>>> #20 0x000000010065c505 in ~CompilerInstance at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Frontend/CompilerInstance.cpp:61
>>>> #21 0x00000001005d6474 in
>>>> clang::tooling::FrontendActionFactory::runInvocation(clang::CompilerInvocation*,
>>>> clang::FileManager*, clang::DiagnosticConsumer*) at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Tooling/Tooling.cpp:270
>>>> #22 0x00000001005d614f in
>>>> clang::tooling::ToolInvocation::runInvocation(char const*,
>>>> clang::driver::Compilation*, clang::CompilerInvocation*) at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Tooling/Tooling.cpp:243
>>>> #23 0x00000001005d5290 in clang::tooling::ToolInvocation::run() at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Tooling/Tooling.cpp:229
>>>> #24 0x00000001005d7b29 in
>>>> clang::tooling::ClangTool::run(clang::tooling::ToolAction*) at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Tooling/Tooling.cpp:360
>>>> #25 0x0000000100566cd2 in
>>>> clang::tidy::runClangTidy(clang::tidy::ClangTidyOptionsProvider*,
>>>> clang::tooling::CompilationDatabase const&,
>>>> llvm::ArrayRef<std::__1::basic_string<char, std::__1::char_traits<char>,
>>>> std::__1::allocator<char> > >,
>>>> std::__1::vector<clang::tidy::ClangTidyError,
>>>> std::__1::allocator<clang::tidy::ClangTidyError> >*) at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/tools/extra/clang-tidy/ClangTidy.cpp:345
>>>> #26 0x0000000100002a96 in main at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/tools/extra/clang-tidy/tool/ClangTidyMain.cpp:145
>>>>
>>>> In short, it appears that ClangTool takes ownership of the diagnostic
>>>> consumer, but it's being allocated on the stack. My fix is to allocate it
>>>> on the heap instead. I've attached my patch. Please let me know if this
>>>> assessment is incorrect, or if you'd like me to go about this differently.
>>>>
>>>
>>> Well, the ownership of the diagnostic consumer shouldn't be transferred,
>>> and I don't see any evidence ClangTool::setDiagnosticConsumer expects this
>>> to happen. This all looks strange, and I'm investigating this.
>>>
>>
>> I wasn't able to reproduce this crash. Your stack trace has
>> ChainedDiagnosticConsumer in it, which afaiu, it is only used twice in
>> Clang, and both places don't seem to be unrelated to clang-tidy. Could you
>> set a breakpoint in ChainedDiagnosticConsumer constructor and send me the
>> stack trace where it gets called in clang-tidy? (or add an "assert(false);"
>> there to get the stack trace on the console in the assertions-enabled build)
>>
>>
>>>
>>>
>>>>
>>>> Thanks!
>>>> Aaron
>>>>
>>>>
>>>> _______________________________________________
>>>> cfe-commits mailing list
>>>> cfe-commits at cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>>>
>>>
>
> On Mon, Jun 23, 2014 at 9:51 AM, Alexander Kornienko <alexfh at google.com>
> wrote:
>
>>
>> On Mon, Jun 23, 2014 at 2:51 PM, Alexander Kornienko <alexfh at google.com>
>> wrote:
>>
>>>
>>> On Thu, Jun 19, 2014 at 5:59 PM, Aaron Wishnick <
>>> aaron.s.wishnick at gmail.com> wrote:
>>>
>>>> When I run clang-tidy on OS X 10.9.3, I immediately get this output:
>>>>
>>>> clang-tidy(97903,0x7fff782fb310) malloc: *** error for object
>>>> 0x7fff5fbfecd0: pointer being freed was not allocated
>>>> *** set a breakpoint in malloc_error_break to debug
>>>>
>>>> This occurs inside the destructor of ClangTidyDiagnosticConsumer.
>>>> Here's my callstack:
>>>>
>>>> #4 0x000000010058e3e2 in ~ClangTidyDiagnosticConsumer at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/tools/extra/clang-tidy/ClangTidyDiagnosticConsumer.h:190
>>>> #5 0x0000000100656a73 in
>>>> std::__1::default_delete<clang::DiagnosticConsumer>::operator()(clang::DiagnosticConsumer*)
>>>> const [inlined] at
>>>> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:2426
>>>> #6 0x0000000100656a4b in
>>>> std::__1::unique_ptr<clang::DiagnosticConsumer,
>>>> std::__1::default_delete<clang::DiagnosticConsumer>
>>>> >::reset(clang::DiagnosticConsumer*) [inlined] at
>>>> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:2625
>>>> #7 0x00000001006569f5 in ~unique_ptr [inlined] at
>>>> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:2593
>>>> #8 0x00000001006569f5 in ~unique_ptr [inlined] at
>>>> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/../lib/c++/v1/memory:2593
>>>> #9 0x00000001006569f5 in ~ChainedDiagnosticConsumer at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/include/clang/Frontend/ChainedDiagnosticConsumer.h:23
>>>> #10 0x0000000100656595 in ~ChainedDiagnosticConsumer at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/include/clang/Frontend/ChainedDiagnosticConsumer.h:23
>>>> #11 0x00000001006565b9 in ~ChainedDiagnosticConsumer at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/include/clang/Frontend/ChainedDiagnosticConsumer.h:23
>>>> #12 0x00000001015eec84 in ~DiagnosticsEngine at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Basic/Diagnostic.cpp:68
>>>> #13 0x00000001015eec35 in ~DiagnosticsEngine at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Basic/Diagnostic.cpp:66
>>>> #14 0x00000001006bd3d3 in
>>>> llvm::RefCountedBase<clang::DiagnosticsEngine>::Release() const at
>>>> /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:55
>>>> #15 0x00000001006bd325 in
>>>> llvm::IntrusiveRefCntPtrInfo<clang::DiagnosticsEngine>::release(clang::DiagnosticsEngine*)
>>>> at /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:90
>>>> #16 0x00000001006bd2fd in
>>>> llvm::IntrusiveRefCntPtr<clang::DiagnosticsEngine>::release() at
>>>> /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:199
>>>> #17 0x00000001006bd2c5 in ~IntrusiveRefCntPtr at
>>>> /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:172
>>>> #18 0x00000001006bbe15 in ~IntrusiveRefCntPtr at
>>>> /Users/awishnick/clang-tidy/llvm/include/llvm/ADT/IntrusiveRefCntPtr.h:172
>>>> #19 0x000000010065cbc1 in ~CompilerInstance at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Frontend/CompilerInstance.cpp:63
>>>> #20 0x000000010065c505 in ~CompilerInstance at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Frontend/CompilerInstance.cpp:61
>>>> #21 0x00000001005d6474 in
>>>> clang::tooling::FrontendActionFactory::runInvocation(clang::CompilerInvocation*,
>>>> clang::FileManager*, clang::DiagnosticConsumer*) at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Tooling/Tooling.cpp:270
>>>> #22 0x00000001005d614f in
>>>> clang::tooling::ToolInvocation::runInvocation(char const*,
>>>> clang::driver::Compilation*, clang::CompilerInvocation*) at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Tooling/Tooling.cpp:243
>>>> #23 0x00000001005d5290 in clang::tooling::ToolInvocation::run() at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Tooling/Tooling.cpp:229
>>>> #24 0x00000001005d7b29 in
>>>> clang::tooling::ClangTool::run(clang::tooling::ToolAction*) at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/lib/Tooling/Tooling.cpp:360
>>>> #25 0x0000000100566cd2 in
>>>> clang::tidy::runClangTidy(clang::tidy::ClangTidyOptionsProvider*,
>>>> clang::tooling::CompilationDatabase const&,
>>>> llvm::ArrayRef<std::__1::basic_string<char, std::__1::char_traits<char>,
>>>> std::__1::allocator<char> > >,
>>>> std::__1::vector<clang::tidy::ClangTidyError,
>>>> std::__1::allocator<clang::tidy::ClangTidyError> >*) at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/tools/extra/clang-tidy/ClangTidy.cpp:345
>>>> #26 0x0000000100002a96 in main at
>>>> /Users/awishnick/clang-tidy/llvm/tools/clang/tools/extra/clang-tidy/tool/ClangTidyMain.cpp:145
>>>>
>>>> In short, it appears that ClangTool takes ownership of the diagnostic
>>>> consumer, but it's being allocated on the stack. My fix is to allocate it
>>>> on the heap instead. I've attached my patch. Please let me know if this
>>>> assessment is incorrect, or if you'd like me to go about this differently.
>>>>
>>>
>>> Well, the ownership of the diagnostic consumer shouldn't be transferred,
>>> and I don't see any evidence ClangTool::setDiagnosticConsumer expects this
>>> to happen. This all looks strange, and I'm investigating this.
>>>
>>
>> I wasn't able to reproduce this crash. Your stack trace has
>> ChainedDiagnosticConsumer in it, which afaiu, it is only used twice in
>> Clang, and both places don't seem to be unrelated to clang-tidy. Could you
>> set a breakpoint in ChainedDiagnosticConsumer constructor and send me the
>> stack trace where it gets called in clang-tidy? (or add an "assert(false);"
>> there to get the stack trace on the console in the assertions-enabled build)
>>
>>
>>>
>>>
>>>>
>>>> Thanks!
>>>> Aaron
>>>>
>>>>
>>>> _______________________________________________
>>>> cfe-commits mailing list
>>>> cfe-commits at cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>>>
>>>
>
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