mapThreadID crashing on Fedora 43

[granitrocky]

On Fedora 43, I am getting a crash when committing a scene. The mapThreadID function inside of common/sys/thread.cpp HERE. This fs >> i is crashing for some reason.

STACKTRACE

#0  std::codecvt<char, char, __mbstate_t>::do_unshift (
    this=0x7fff82a741f0 <(anonymous namespace)::codecvt_w>, 
    __to=0xffffffff <error: Cannot access memory at address 0xffffffff>, 
    __to_next=<error reading variable: Cannot access memory at address 0xffffffff>) at ../../../../../libstdc++-v3/src/c++98/codecvt.cc:74
#1  0x00007fff828952d7 in std::num_get<char, std::istreambuf_iterator<char, std::char_traits<char> > >::get (this=<optimized out>, __in=..., 
    __end=..., __io=..., __err=@0x7fffffffabb4: std::_S_goodbit, 
    __v=@0x7fffffffabb8: 140737488333952)
    at /usr/src/debug/gcc-15.2.1-7.fc43.x86_64/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/include/bits/locale_facets.h:2048
#2  std::basic_istream<char, std::char_traits<char> >::operator>> (
    this=0x7fffffffacf0, __n=@0x7fffffffacd0: 0)
    at /usr/src/debug/gcc-15.2.1-7.fc43.x86_64/obj-x86_64-redhat-linux/x86_64-redhat-linux/libstdc++-v3/include/bits/istream.tcc:201
#3  0x00007fff7b04fa90 in embree::mapThreadID (threadID=threadID@entry=1)
    at /opt/gd-fmod-steam-audio/inc/steam-audio/core/deps-build/embree/src/embree/common/sys/thread.cpp:191
#4  0x00007fff7b05043d in embree::createThread (
    f=f@entry=0x7fff7b053850 <embree::threadPoolFunction(std::pair<embree::TaskScheduler::ThreadPool*, unsigned long>*)>, arg=0x1e7e6760, 
    stack_size=stack_size@entry=4194304, threadID=1)
    at /opt/gd-fmod-steam-audio/inc/steam-audio/core/deps-build/embree/src/embree/common/sys/thread.cpp:403
#5  0x00007fff7b052881 in embree::TaskScheduler::ThreadPool::setNumThreads
    (this=0x172c17a0, newNumThreads=<optimized out>, 
    startThreads=<optimized out>)
    at /opt/gd-fmod-steam-audio/inc/steam-audio/core/deps-build/embree/src/embree/common/tasking/taskschedulerinternal.cpp:171
#6  0x00007fff794e0f46 in embree::TaskScheduler::spawn_root<embree::Scene::commit_internal(bool)::<lambda()> > (size=1, this=0x205178c0, closure=..., 
    context=0x7fffffffb200, useThreadPool=true)
    at /opt/gd-fmod-steam-audio/inc/steam-audio/core/deps-build/embree/src/embree/kernels/common/../../common/tasking/taskschedulerinternal.h:261

[granitrocky]

I think the crash is because of the unshift operator, >>, trying to coerce a char to int. When I change the type to char, the crash goes away.

[svenwoop]

You will only run into that code if you did explicitely set set_affinity=1 during Embree device construction. Do you do this on purpose? By default your app should not affinitize theads, thus best remove that affinity config.

Why it crashes is not clear, think that should never happen but that read should fail at some point and never crash.

[granitrocky]

The app I'm using is actually Valve's Steam Audio SDK. I recently migrated to Fedora 43, and that's when this particular crash started happening. I will see if they are setting the affinity in their app, but if there's a bug in this code I think it should be fixed since the option for affinity is still there.

EDIT: I can confirm that explicitly setting "affinity=0" in the Steam Audio SDK when initializing the embree device makes the crash go away.

[svenwoop]

Still not sure how that crash can happen. I think we should just remove that mapThreadID function altogether, it is not really important. @stefanatwork what do you think?

[granitrocky]

It must be related to some change in libstdc++ that changed the way that fstream reads the formatted output. The threads_list file has a comma in it, and the i value is defined as an int, so under the hood the cpp code tries to map, in my case, "0,12" to an int value.

Changingi to char fixes that.