svn commit: r330285 - head/sys/sys

[Brooks Davis]

On Fri, Mar 02, 2018 at 12:43:34PM -0500, Pedro Giffuni wrote:
> (cc in Eitan as he may be interested in the extra restrict cases)
> 
> 
> On 02/03/2018 11:47, Konstantin Belousov wrote:
> > Author: kib
> > Date: Fri Mar  2 16:47:02 2018
> > New Revision: 330285
> > URL: https://svnweb.freebsd.org/changeset/base/330285
> >
> > Log:
> >    Remove _Nonnull attributes from user addresses arguments for
> >    copyout(9) family.
> >    
> >    The addresses are user-controllable, and if the process ABI allows
> >    mapping at zero, then the zero address is meaningful, contradicting
> >    the definition of _Nonnull.  In any case, it does not require any
> >    special code to handle NULL udaddr.
> >    
> 
> FWIW, the _Nonnull attributes didn't do much at all beyond producing a 
> warning.
> They replaced the GNU __nonnull() attributes which were much more dangerous.
> I am OK with seeing both gone here though.

Even if the process ABI doesn't allow mapping at NULL, we have code that
depends on copyout(NULL, foo, 0) being a nop.

-- Brooks
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