passing NULL to clock_getres (VDSO): terminated by unexpected signal 11

[David Laight]

From: Thomas Gleixner
> Sent: 20 October 2019 20:53
> On Sun, 20 Oct 2019, Andreas Schwab wrote:
> > On Okt 20 2019, Thomas Gleixner wrote:
> >
> > > POSIX does not mention anything about the validity of the pointer handed to
> > > clock_getres().
> >
> > Sure it does: "If the argument res is not NULL, the resolution of the
> > specified clock shall be stored in the location pointed to by res.  If
> > res is NULL, the clock resolution is not returned.".
> 
> Sigh, that makes a lot of sense - NOT.
> 
> But for the sake of making a non-sensical specification happy we can add a
> NULL pointer check for this. The interesting question is what should be
> returned in this case. The kernel returns EFAULT which is probably not
> POSIX compliant either.

The application won't see errno == EFAULT.
EFAULT gets converted to SIGSEGV (probably) in the return-to-user code path.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)