[Bug libc/23296] Data race in setting function descriptor during lazy binding

["carlos at redhat dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=23296

--- Comment #2 from Carlos O'Donell <carlos at redhat dot com> ---
(In reply to John David Anglin from comment #1)
> After thinking about this, I don't believe this can be fixed in glibc.
> 
> 1) The window for the race could be reduced by atomically updating function
> descriptors but the race can't be fully eliminated.  See for example the
> linker
> stub shown at the end of comment #1.  Function descriptors would have to have
> 8 byte alignment.
> 
> 2) Even if we could detect the case where the function descriptor has been
> updated between the loading of the ip and gp values, there's no way to find
> the function descriptor and correct the ip value.
> 
> So, I think we should link pthread executables and shared libraries with
> "-z now".

You have not described the race.

Could you please describe the race in detail?

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