Linux 4.1: FATAL: ThreadSanitizer: unexpected memory mapping

[ramosian-glider]

Originally reported on Google Code with ID 96

With Linux 4.1 and gcc 4.9 or 5.2 I get this error:

$ echo 'void main(void){}' | gcc -pie -fPIE -fsanitize=thread -xc - && ./a.out
FATAL: ThreadSanitizer: unexpected memory mapping 0x55d400945000-0x55d40094600

It seems that this commit (thanks to Ben Hutchings for finding it) is change is the
root of the problem: 
https://git.kernel.org/linus/d1fd836dcf00d2028c700c7e44d2c23404062c90

Related: http://bugs.debian.org/796246

Reported by jrobert.pro on 2015-08-21 12:33:55

[ramosian-glider]

The same bug for MSan:
https://llvm.org/bugs/show_bug.cgi?id=24155

I thought TSan would not be affected by this. Is that a GCC vs Clang difference?

Reported by eugenis@google.com on 2015-08-21 19:03:25

[ramosian-glider]

This bug in the GCC bugtracker: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67308

Reported by jrobert.pro on 2015-08-22 14:38:03

[ramosian-glider]

May also be relevant for ASan.

Reported by tetra2005x on 2015-08-24 06:08:41

[dvyukov]

Latest tsan runtime supports non-pie binaries. Non-pie tsan binaries should work with 4.1, right?

[jeromerobert]

Yes they do (tested with gcc 5.2 and Linux 4.2). So I guess this bug is now just about the documentation.

[milianw]

Hey all,

Qt builds all its code in PIE/PIC mode. Thus this bug prevents it from being used on all of the Qt ecosystem. I don't think it's just about fixing the documentation, I hope you guys can find a way to make the sanitizers work with PIE/PIC binaries.

If anyone has a patch for me to try out, I'd gladly do that.

Thanks for the Sanitizers!

[dvyukov]

Qt builds all its code in PIE/PIC mode. Thus this bug prevents it from being used on all of the Qt ecosystem.

FWIW this does not prevent tsan to be used with tsan. Qt does not build its code with -fsanitize-thread either. Whoever does a separate tsan build can also remove -pie.

[gpakosz]

Why is this issue closed?

As far as I understand, the current status is that TSAN doesn't need -fpie anymore which defines a workaround for newer Linux kernels: don't compile with -fpie.

But that doesn't solve the Linux 4.1 + TSAN + -fpie equation.

Did I get it right?

[dvyukov]

@gpakosz This is issue is not closed.
It's "misc/cgo/testsanitizers: fails on Ubuntu 16.10" that is closed.

[gpakosz]

Damn you're so right. I'm sorry I mixed up statuses

[lilianmoraru]

This error usually appears when people forget to export LD_PRELOAD before running the application.
Example on Ubuntu, 64-bit, gcc 5:

export LD_PRELOAD="/usr/lib/gcc/x86_64-linux-gnu/5/libtsan.so"
./binary # running the application compiled with tsan

Hope this helps.

[dvyukov]

@lilianmoraru You don't need to LD_PRELOAD tsan runtime. That's wrong and is not guaranteed to work.

[dvyukov]

Fixed upstream by http://llvm.org/viewvc/llvm-project?rev=282152&view=rev