Re: [PATCH] malloc: Use compat_symbol_reference in libmcheck [BZ #22050]

[Florian Weimer <fweimer at redhat dot com>]

On 08/31/2017 06:02 PM, Joseph Myers wrote:
> On Thu, 31 Aug 2017, Florian Weimer wrote:
> 
>> Interposition happens only if __malloc_initialize_hook is listed in the
>> .dynsym section of the executable.  At least some versions of binutils
>> will not add the symbol to the .dynsym section if it is unversioned and
>> there is a definition in a DSO which lacks a default version.  Arguably
>> this is a bug in the link editor.
> 
> Sounds like a feature to me, not a bug.  After all, it's essentially what 
> makes it possible for us to obsolete (stop working for new programs as far 
> as possible) symbols whose interface is that the program interposes them, 
> such as matherr.  Effectively, a DSO definition that lacks a default 
> version should be treated exactly the same at static link time as no DSO 
> definition at all.

But that's not what happens if you compile with --export-dynamic.  That
--export-dynamic changes behavior here is very surprising.  That's why I
think this could be considered a bug in the link editor.

Thanks,
Florian