Re: [PATCHv3 0/4] sys_indirect system call

Eric Dumazet
2007-11-19T16:15:13Z

On Mon, 19 Nov 2007 07:48:23 -0800
Ulrich Drepper <drepper@redhat.com> wrote:

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> Eric Dumazet wrote:
> > So when you recompile your old program (as you post it and as I commented on),
> > it will pass a >= 12 bytes data to kernel, with only first 4 bytes set to O_CLOEXEC.
> >
> > Other bytes will contain junk
>
> If you don't initialize the entire structure and you use it all, of
> course you get undefined behavior. That's nothing new. The program I
> attached is not an example, it's a test for the functionality in this patch.
>
> Like with every kernel interface, you have to use it correctly. The
> good news is that user programs should never use this syscall directly
> (just like don't for existing ones).
>
> I see no problem at all here.

I do see a problem, because some readers will take your example as a reference,
as it will probably sit in a page that google^Wsearch_engines will bring at the
top of search results for next ten years or so.

(I bet for "sys_indirect syscall" -> http://lwn.net/Articles/258708/ )

Next time you post it, please warn users that it will break in some years, or
state clearly this should only be used internally by glibc.

Thank you