Re: [PATCH] elf/dl-load.c: Remove local_strdup.

["Carlos O'Donell" <carlos at redhat dot com>]

On 10/24/2014 05:40 PM, Roland McGrath wrote:
>> I see that __strsep in dl-load.c is called with double underscore,
>> but why not strlen? Is it because for these routines, which are
>> always in ld.so, we rely on the ld.so copies of them?
> 
> strlen is part of the most restricted name space (C89).  strsep and strdup
> are not.  Remember that this code can also be linked statically (it's part
> of libc.a).  In ld.so proper, it doesn't matter concretely because it does
> not export these symbols and so will always use its own copies.

Thanks it's the static case I had forgotten to take into account.

>> I also thought for a second that a strcpy that went into the PLT
>> would trigger check-localplt failures, but then I saw ld.so is not
>> part of that test? Any reason why not?
> 
> It's a surprise to me too, and I had to check to convince myself it really
> wasn't tested somehow.  I don't see any reason it shouldn't be per se.  Add
> it to the list and verify nothing goes wrong.  But there are reasons it's
> far less likely ever to be a problem.  ld.so has no dependencies and is
> built with -z defs, so it can never have undefined references and can never
> have PLT entries for anything but its own exported symbols (unless the
> linker grows new bugs).  There is a very small set of exported symbols
> (elf/Versions) that almost never changes.

I'll do that now and commit as obvious. I can't see anyone objecting to
me touching arch localplt.data files.

Cheers,
Carlos.