gcc -fsanitize=leak crashes immediately

[Alexandre Ferrieux]

The Leak Sanitizer in the gcc version bundled with Ubuntu 20.04.6 LTS has a fatal issue that makes the compiled program crash immediately (even before main()) with:

  ==28797==Sanitizer CHECK failed: ../../../../src/libsanitizer/lsan/lsan_interceptors.cpp:53
  ((!lsan_init_is_running)) != (0) (0, 0)

This can be exercised even with a trivial program like this one:

  #include <stdio.h>
  #include <stdlib.h>

  int main(int argc,char **argv)
  {
    void *x;

    x=malloc(1789);
    printf("Hey I managed to allocate pointer %p !!!\n",x);
    free(x);

    exit(0);
  }

compiled with

  gcc -fsanitize=leak foo.c

Then executing "./a.out" yields the above error.

The root cause is an unwarranted assumption that "dlopen() calls only calloc()".
Specific code in liblsan.so allows to solve the chicken-and-egg problem between "dlopen calls calloc" and "instrumenting calloc needs dlopen", and thanks to this, __lsan_init() can then heavily call dlopen(). However, no such thing is done for malloc(), which nowadays is also called by dlopen(). As a result, within __lsan_init(), an unprotected malloc() is called by dlopen(), yielding an assert (as the instrumented malloc refuses execution during init).

The initial detection, analysis and (brutal) workaround are documented here:
https://github.com/magma/magma/issues/15279#issuecomment-1742247833

This bug has been fixed in gcc11+ (by reimplementation of a clean dlopen-specific allocator), but not in gcc9 or gcc10 (which are EOS).
The consequence is that gcc -fsanitize=leak is unusable on 20.04.6 LTS.

---

Description: Ubuntu 20.04.6 LTS
Release: 20.04

gcc:
  Installed: 4:9.3.0-1ubuntu2
  Candidate: 4:9.3.0-1ubuntu2
  Version table:
 *** 4:9.3.0-1ubuntu2 500
        500 http://fr.archive.ubuntu.com/ubuntu focal/main amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gcc 4:9.3.0-1ubuntu2
ProcVersionSignature: Ubuntu 5.4.0-26.30-generic 5.4.30
Uname: Linux 5.4.0-26-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.27
Architecture: amd64
CasperMD5CheckResult: skip
Date: Tue Oct 3 23:51:25 2023
InstallationDate: Installed on 2023-06-22 (103 days ago)
InstallationMedia: Ubuntu 20.04.6 LTS "Focal Fossa" - Release amd64 (20230316)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: gcc-defaults
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.