Re: [PATCH] libio: use PTR_MANGLE/PTR_DEMANGLE for FILE vtables

[Kees Cook <kees at outflux dot net>]

On Fri, Dec 23, 2011 at 10:51:33AM -0800, Kees Cook wrote:
> On Fri, Dec 23, 2011 at 01:37:06PM -0500, Ulrich Drepper wrote:
> > This causes binary compatibility issues.  Otherwise it would have long
> > since been done.
> 
> Ah, dang. What's the situation it causes? The test suite entirely passed
> after making this change, so I was hopeful. Could some kind of compat mode
> be introduced to handle the other cases? I'd be happy to try to work it
> out, but I'm not sure how to recreate the failure condition you mean.

Perhaps a better way to phrase this is, "what creates _IO_FILE_plus
structures that are outside of glibc?" Right now, it looks like everything
I can find is in glibc itself, so I remain unclear why this patch would
create an ABI problem.

-- 
Kees Cook                                            @outflux.net