On Fri, Jul 03, 2020 at 08:52:05AM -0700, Kees Cook wrote:
> On Fri, Jul 03, 2020 at 04:44:27PM +0100, Will Deacon wrote:
> > On Fri, Jul 03, 2020 at 08:17:19AM -0700, Kees Cook wrote:
> > > On Fri, Jul 03, 2020 at 09:39:14AM +0100, Will Deacon wrote:
> > > > diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> > > > index 5f5b868292f5..a13661f44818 100644
> > > > --- a/arch/arm64/kernel/syscall.c
> > > > +++ b/arch/arm64/kernel/syscall.c
> > > > @@ -121,12 +121,10 @@ static void el0_svc_common(struct pt_regs *regs,
> > > > int scno, int sc_nr,
> > > > user_exit();
> > > >
> > > > if (has_syscall_work(flags)) {
> > > > - /* set default errno for user-issued syscall(-1) */
> > > > - if (scno == NO_SYSCALL)
> > > > - regs->regs[0] = -ENOSYS;
> > > > - scno = syscall_trace_enter(regs);
> > > > - if (scno == NO_SYSCALL)
> > > > + if (syscall_trace_enter(regs))
> > > > goto trace_exit;
> > > > +
> > > > + scno = regs->syscallno;
> > > > }
> > > >
> > > > invoke_syscall(regs, scno, sc_nr, syscall_table);
> > >
> > > What effect do either of these patches have on the existing seccomp
> > > selftests: tools/testing/selftests/seccomp/seccomp_bpf ?
> >
> > Tests! Thanks, I'll have a look.
>
> Thanks!
>
> (And either way, that this behavioral difference went unnoticed means we
> need to add a test to the selftests for this patch.)
Unsurprisingly, I don't think the tests go near this. I get 75/77 passes
on arm64 defconfig with or without these changes.
We could add a test, but then we'd have to agree on what it's supposed to
be doing ;)
Will
