[Bug 1894166] [gcc-9/focal] verification still needed

[Brian Murray]

The fix for this bug has been awaiting testing feedback in the -proposed
repository for focal for more than 90 days.  Please test this fix and
update the bug appropriately with the results.  In the event that the
fix for this bug is still not verified 15 days from now, the package
will be removed from the -proposed repository.

** Tags added: removal-candidate

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https://bugs.launchpad.net/bugs/1894166

Title:
  libasan missing debug symbols break debugging

Status in gcc-10 package in Ubuntu:
  Fix Released
Status in gcc-9 package in Ubuntu:
  Fix Released
Status in gcc-10 source package in Focal:
  Fix Released
Status in gcc-9 source package in Focal:
  Fix Committed
Status in gcc-10 source package in Groovy:
  Fix Released
Status in gcc-9 source package in Groovy:
  Fix Committed

Bug description:
  By default, all symbols are missing from libasan binary that is
  installed with this package. This, among other things, effectively
  breaks debugging with gdb (and LLDB , but that doesn't matter).

  To be able to catch ASAN errors in GDB , one would break on
  "__sanitizer::Die" and go from there, but without symbols, this won't
  work. Other tools rely on symbol lookups to determine instrumentation
  presence , which would fail in this case as well.

  For example, without libasan5-dbgsym  installed:

  (gdb) break __sanitizer::Die
  Function "__sanitizer::Die" not defined.
  Make breakpoint pending on future shared library load? (y or [n]) y
  Breakpoint 1 (__sanitizer::Die) pending.
  (gdb) r
  ...
  ASAN REPORT
  ...
  ==1802381==ABORTING
  [Inferior 1 (process 1802381) exited with code 01]

  However, with libasan5-dbgsym installed:

  (gdb) break __sanitizer::Die
  Breakpoint 1 at 0x7ffff76bc200: file ../../../../src/libsanitizer/sanitizer_common/sanitizer_termination.cc, line 49.
  (gdb) r
  ...
  ASAN REPORT
  ...
  ==1805058==ABORTING

  Breakpoint 1, __sanitizer::Die () at ../../../../src/libsanitizer/sanitizer_common/sanitizer_termination.cc:49
  49      ../../../../src/libsanitizer/sanitizer_common/sanitizer_termination.cc: No such file or directory.
  (gdb) bt
  #0  __sanitizer::Die () at ../../../../src/libsanitizer/sanitizer_common/sanitizer_termination.cc:49
  #1  0x00007ffff769d8ec in __asan::ScopedInErrorReport::~ScopedInErrorReport (this=0x7fffffffd156, __in_chrg=<optimized out>)
      at ../../../../src/libsanitizer/asan/asan_report.cc:185
  #2  0x00007ffff769d363 in __asan::ReportGenericError (pc=93824992236075, bp=bp at entry=140737488346576, sp=sp at entry=140737488346560, addr=106034152603909,
      is_write=is_write at entry=false, access_size=access_size at entry=1, exp=0, fatal=true) at ../../../../src/libsanitizer/asan/asan_report.cc:192
  #3  0x00007ffff769de4b in __asan::__asan_report_load1 (addr=<optimized out>) at ../../../../src/libsanitizer/asan/asan_rtl.cc:116
  #4  0x000055555555522b in main ()
  (gdb)

  
  In this example, it's fairly obvious that missing symbols will prevent one to put a breakpoint on __sanitizer::Die , but as I mentioned, checks in other tools would fail silently and the issue isn't immediately traceable back to missing symbols. 

  Since AddressSanitizer is primarily used for debugging anyway, would
  it make sense to have libasan with symbols by default?

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