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SubjectRe: [5.2 REGRESSION] Generic vDSO breaks seccomp-enabled userspace on i386
On Sun, 28 Jul 2019, Arnd Bergmann wrote:

> On Sun, Jul 28, 2019 at 12:30 PM Thomas Gleixner <tglx@linutronix.de> wrote:
> > On Sun, 28 Jul 2019, Arnd Bergmann wrote:
> > > On Sat, Jul 27, 2019 at 7:53 PM Andy Lutomirski <luto@kernel.org> wrote:
>
> > Which is totally irrelevant because res is NULL and that NULL pointer check
> > should simply return -EFAULT, which is what the syscall fallback returns
> > because the pointer is NULL.
> >
> > But that NULL pointer check is inconsistent anyway:
> >
> > - 64 bit does not have it and never had
> >
> > - the vdso is not capable of handling faults properly anyway. If the
> > pointer is not valid, then it will segfault. So just preventing the
> > segfault for NULL is silly.
> >
> > I'm going to just remove it.
>
> Ah, you are right, I misread.
>
> Anyway, if we want to keep the traditional behavior and get fewer surprises
> for users of seccomp and anything else that might observe clock_gettime
> behavior, below is how I'd do it. (not even build tested, x86-only. I'll
> send a proper patch if this is where we want to take it).

I posted a series which fixes up the mess 2 hours before you sent this mail :)

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