search

Qucs / qucsator

Circuit simulator of the Qucs project
http://qucs.sourceforge.net
GNU General Public License v2.0
23 stars 12 forks source link

Simulator crashes with glibc 2.33 #29

Closed Lacsapix closed 3 years ago

Lacsapix commented 3 years ago

Trying to simulate a simple voltage divider, the simulation crashes with the following helpfull message: "ERROR: Simulator crashed!"

Digging a bit around I did: 

qucsator -i netlist.txt

And it provided a bit more help, a coredump:

/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../include/c++/10.2.0/bits/stl_vector.h:1045: std::vector::reference std::vector<qucs::nodelist_t *, std::allocator<qucs::nodelist_t *>>::operator[](std::vector::size_type) [_Tp = qucs::nodelist_t *, _Alloc = std::allocator<qucs::nodelist_t *>]: Assertion '__builtin_expect(__n < this->size(), true)' failed.
Aborted (core dumped)

Researching a bit more: I found that the following code provides the same error https://github.com/rstudio/httpuv/issues/133#issuecomment-387499519

This led me to believe that glibc might be the culprit here. Surely enough when browsing through the Archlinux forums My suspicion was confirmed by the (current) top post on the AUR page of QUCS https://aur.archlinux.org/packages/qucs/. It seems the upgrade from glibc 2.25 to version 2.xx throws this error. Running the same simulation on a different computer (also an archlinux pc) with hasn't upgraded in months, seems to work fine.

Of course its Archlinux which is known for having crashes when upgrading packages to soon. But since more Distro's are likely to follow, it will come up more often.

netlist.txt

felix-salfelder commented 3 years ago

It seems the upgrade from glibc 2.25 to version 2.xx throws this error.

To narrow it down, on debian your netlist seems to work with qucsator 0.0.20 linked against libc6:amd64 2.31-3 (which I suppose means glibc 2.31).

But maybe it has to do with compile time flags. Something like -D_GLIBCXX_ASSERTIONS could have exposed a bug worth fixing...

Lacsapix commented 3 years ago

Yes I've found that flag as well. Another note to add: I've upgraded my "different computer" to the latest archlinux repo's (with glibc 2.33-5) and qucs still works...... So this a bit more strange than I initially thought. Maybe another missing dependency. EDIT: Nope!!! Still crashes, I re-build qucs and it now throws the same error.... dammit

felix-salfelder commented 3 years ago

I tried on Debian with g++-{9,10,11}. A production build does not crash (maybe this is where the glibc version comes in), but a build with -D_GLIBCXX_ASSERTIONS exposes the bug.

In particular, I can now test/merge a patch if you send one.

ckoegler commented 3 years ago

I am working on this.

ckoegler commented 3 years ago

The problem was the write access to std vector narray narray[0] = n; and narray[i] = n; in function nodelist::assignNodes before reserving this memory properly.

allep commented 3 years ago

Confirmed also on Fedora 34 with:

felix-salfelder commented 3 years ago

On Wed, Aug 04, 2021 at 02:15:32AM -0700, Alessandro Paganelli wrote:

Confirmed also on Fedora 34 with:

  • Qucs 0.0.19
  • Qucsator 0.0.19
  • glibc 2.33-20-fc34

Thanks for confirmation. It has been fixed (partially) with #30, merged into develop.

The crash is not a big surprise when you look at the code. But we are not sure if there might be more instances of this. Please test the fixed version.

Please check if you could use Qucsator 0.0.20 instead, on Fedora.

allep commented 3 years ago

A newer package is not available on Fedora 34. I rebuilt it from tag 0.0.20 as you suggested and now everything works fine. Thanks!

felix-salfelder commented 3 years ago

Thanks. Please open a new issue if there's more of this.