Qt protobuf double free or invalid pointer error

[SebiSebi]

I have tried to use protocol buffers in a Qt Application. The main function is:

#include <QApplication>
#include "../../proto/client_config.pb.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    return 0;
}

I have linked the binary with -lprotobuf and run the code. It gives me the following runtime error:

*** Error in `/home/sebisebi/Anul3/IP/instant_messenger/src/build-ClientApplication-Desktop_Qt_5_8_0_GCC_64bit-Debug/ClientApplication': free(): invalid pointer: 0x0000000000985e50 ***
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x777e5)[0x7f874793f7e5]
/lib/x86_64-linux-gnu/libc.so.6(+0x7fe0a)[0x7f8747947e0a]
/lib/x86_64-linux-gnu/libc.so.6(cfree+0x4c)[0x7f874794b98c]
/usr/lib/x86_64-linux-gnu/libprotobuf-lite.so.9(_ZN6google8protobuf8internal28DestroyDefaultRepeatedFieldsEv+0x1f)[0x7f873464b49f]
/usr/lib/x86_64-linux-gnu/libprotobuf.so.9(_ZN6google8protobuf23ShutdownProtobufLibraryEv+0x8b)[0x7f87491c7b3b]
/usr/lib/x86_64-linux-gnu/libmirprotobuf.so.3(+0x20329)[0x7f8734a91329]
/lib64/ld-linux-x86-64.so.2(+0x10c17)[0x7f87494a8c17]
/lib/x86_64-linux-gnu/libc.so.6(+0x39ff8)[0x7f8747901ff8]
/lib/x86_64-linux-gnu/libc.so.6(+0x3a045)[0x7f8747902045]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf7)[0x7f87478e8837]
/home/sebisebi/Anul3/IP/instant_messenger/src/build-ClientApplication-Desktop_Qt_5_8_0_GCC_64bit-Debug/ClientApplication[0x405679]

If I do not link protobuf library (not using -lprotobuf) the code compiles (since I am not using ClientConfig class at all) and it does not raise any error at runtime.

I cannot figure out what is the problem with this. It seems very strange. Moreover, if I do not define the QApplication object in the main's first line the crash does not occur. I have installed protobuf compiler and libraries using apt-get install protobuf-compiler libprotoguf-dev and the current version is 2.6.1.

[Kentzo]

Wild guess: you have different protobuf linked against your app directly and through some other dependency.

[SebiSebi]

Yes, you were right. I have managed to solve the problem by reinstalling the protobuf compiler and libraries.

[HWiese1980]

I've got the same issue with some of my apps here. Is there some fancy tool by chance that can help me track the issue down? I mean, like a GUI maybe that shows me a dependency/library import tree or something?

[Kentzo]

@HWiese1980 It depends on the platform. On Linux you have ldd, on Windows there is Dependency Walker and on macOS there is otool.

[HWiese1980]

@Kentzo I know about ldd, thanks. But it's clumsy and uncomfortable to get a complete dependency graph with it. I'm looking for something with a GUI. Something that can visualize the graph. Maybe even something that is able to detect conflicts.

[arya-coding]

Hi guys,

I had the exact same issue using Caffe. I found the fix on an another repo : CMU-Perceptual-Computing-Lab/openpose#68 (comment)