vglavnyy
commented
5 years ago Thank you for the report. This can be false positive due to hidden mutually exclusive conditions.
Can you reproduce this conditional flow in run-time as an isolated unit-test in the test.cpp?
Flatbuffers cmake script has the ability to enable ASAN and UBSAN for the flattests target using -DFLATBUFFERS_CODE_SANITIZE=ON flag.
JerryJoyce
Language: c++ Compiler: clang version 6.0.0-1ubuntu2 OS: Ubuntu 18.04 FBVersion: 1.10
In my schema I have an element of type uint64. When I call the method to create an instance of this schema, the compiler thinks there is a potential memory leak. I really don't want to disable this compiler check.
Here is the clang analysis:
/go/src/RaaS.PerceptionEngine.Core/libArchon/Archon/src/api.cpp:159:22: note: Calling 'CreateArchonMessage' auto archonMsg = CreateArchonMessage(builder, ^ /go/src/RaaS.PerceptionEngine.Core/libArchon/build/io/gencpp/archonmessage_generated.h:157:3: note: Calling 'ArchonMessageBuilder::addTimeStamp' builder.add_TimeStamp(TimeStamp); ^ /go/src/RaaS.PerceptionEngine.Core/libArchon/build/io/gencpp/archonmessagegenerated.h:117:5: note: Calling 'FlatBufferBuilder::AddElement' fbb.AddElement(ArchonMessage::VT_TIMESTAMP, TimeStamp, 0);
^
/usr/local/include/flatbuffers/flatbuffers.h:1032:9: note: Left side of '&&' is true
if (e == def && !forcedefaults) return;
^
/usr/local/include/flatbuffers/flatbuffers.h:1032:21: note: Assuming the condition is false
if (e == def && !forcedefaults) return;
^
/usr/local/include/flatbuffers/flatbuffers.h:1032:5: note: Taking false branch
if (e == def && !forcedefaults) return;
^
/usr/local/include/flatbuffers/flatbuffers.h:1034:5: note: Calling 'FlatBufferBuilder::TrackField'
TrackField(field, off);
^
/usr/local/include/flatbuffers/flatbuffers.h:1024:5: note: Calling 'vector_downward::scratch_pushsmall'
buf.scratch_push_small(fl);
^
/usr/local/include/flatbuffers/flatbuffers.h:719:5: note: Calling 'vector_downward::ensure_space'
ensure_space(sizeof(T));
^
/usr/local/include/flatbuffers/flatbuffers.h:665:5: note: Taking true branch
if (len > static_cast(cur - scratch)) { reallocate(len); }
^
/usr/local/include/flatbuffers/flatbuffers.h:665:55: note: Calling 'vector_downward::reallocate'
if (len > static_cast(cur - scratch)) { reallocate(len); }
^
/usr/local/include/flatbuffers/flatbuffers.h:776:29: note: Assuming 'old_reserved' is 0
old_reserved ? old_reserved / 2 : initialsize);
^
/usr/local/include/flatbuffers/flatbuffers.h:776:29: note: '?' condition is false
/usr/local/include/flatbuffers/flatbuffers.h:778:9: note: Assuming the condition is false
if (buf) {
^
/usr/local/include/flatbuffers/flatbuffers.h:778:5: note: Taking false branch
if (buf) {
^
/usr/local/include/flatbuffers/flatbuffers.h:782:14: note: Calling 'Allocate'
buf = Allocate(allocator, reserved_);
^
/usr/local/include/flatbuffers/flatbuffers.h:431:10: note: Assuming 'allocator' is null
return allocator ? allocator->allocate(size)
^
/usr/local/include/flatbuffers/flatbuffers.h:431:10: note: '?' condition is false
/usr/local/include/flatbuffers/flatbuffers.h:432:22: note: Calling 'DefaultAllocator::allocate'
: DefaultAllocator().allocate(size);
^
/usr/local/include/flatbuffers/flatbuffers.h:418:12: note: Memory is allocated
return new uint8t[size];
^
/usr/local/include/flatbuffers/flatbuffers.h:432:22: note: Returned allocated memory
: DefaultAllocator().allocate(size);
^
/usr/local/include/flatbuffers/flatbuffers.h:782:14: note: Returned allocated memory
buf = Allocate(allocator, reserved);
^
/usr/local/include/flatbuffers/flatbuffers.h:665:55: note: Returned allocated memory
if (len > static_cast(cur - scratch)) { reallocate(len); }
^
/usr/local/include/flatbuffers/flatbuffers.h:719:5: note: Returned allocated memory
ensurespace(sizeof(T));
^
/usr/local/include/flatbuffers/flatbuffers.h:1024:5: note: Returned allocated memory
buf.scratch_push_small(fl);
^
/usr/local/include/flatbuffers/flatbuffers.h:1034:5: note: Returned allocated memory
TrackField(field, off);
^
/go/src/RaaS.PerceptionEngine.Core/libArchon/build/io/gencpp/archonmessagegenerated.h:117:5: note: Returned allocated memory
fbb.AddElement(ArchonMessage::VT_TIMESTAMP, TimeStamp, 0);
^
/go/src/RaaS.PerceptionEngine.Core/libArchon/build/io/gencpp/archonmessagegenerated.h:157:3: note: Returned allocated memory
builder.add_TimeStamp(TimeStamp);
^
/go/src/RaaS.PerceptionEngine.Core/libArchon/Archon/src/api.cpp:159:22: note: Returned allocated memory
auto archonMsg = CreateArchonMessage(builder,
^
/go/src/RaaS.PerceptionEngine.Core/libArchon/Archon/src/api.cpp:171:5: note: Calling 'FlatBufferBuilder::Finish'
builder.Finish(archonMsg);
^
/usr/local/include/flatbuffers/flatbuffers.h:1700:5: note: Calling 'FlatBufferBuilder::Finish'
Finish(root.o, file_identifier, false);
^
/usr/local/include/flatbuffers/flatbuffers.h:1725:15: note: '?' condition is false
PreAlign((size_prefix ? sizeof(uoffset_t) : 0) + sizeof(uoffset_t) +
^
/usr/local/include/flatbuffers/flatbuffers.h:1726:19: note: '?' condition is false
(file_identifier ? kFileIdentifierLength : 0),
^
/usr/local/include/flatbuffers/flatbuffers.h:1725:5: note: Calling 'FlatBufferBuilder::PreAlign'
PreAlign((size_prefix ? sizeof(uoffset_t) : 0) + sizeof(uoffset_t) +
^
/usr/local/include/flatbuffers/flatbuffers.h:1179:5: note: Calling 'vectordownward::fill'
buf.fill(PaddingBytes(GetSize() + len, alignment));
^
/usr/local/include/flatbuffers/flatbuffers.h:727:5: note: Calling 'vector_downward::make_space'
make_space(zero_pad_bytes);
^
/usr/local/include/flatbuffers/flatbuffers.h:673:20: note: Calling 'vector_downward::ensure_space'
size_t space = ensure_space(len);
^
/usr/local/include/flatbuffers/flatbuffers.h:665:5: note: Taking true branch
if (len > static_cast(cur - scratch)) { reallocate(len); }
^
/usr/local/include/flatbuffers/flatbuffers.h:665:55: note: Calling 'vector_downward::reallocate'
if (len > static_cast(cur - scratch)) { reallocate(len); }
^
/usr/local/include/flatbuffers/flatbuffers.h:776:29: note: '?' condition is true
old_reserved ? old_reserved / 2 : initialsize);
^
/usr/local/include/flatbuffers/flatbuffers.h:778:5: note: Taking true branch
if (buf_) {
^
/usr/local/include/flatbuffers/flatbuffers.h:786:3: note: Potential memory leak
}
^