svn commit: r348843 - head/sys/vm

[Shawn Webb]

On Tue, Jun 11, 2019 at 01:33:23AM +1000, Bruce Evans wrote:
> On Mon, 10 Jun 2019, Shawn Webb wrote:
> 
> > On Mon, Jun 10, 2019 at 03:07:11AM +0000, Doug Moore wrote:
> > > ...
> > > Log:
> > >   There are times when a len==0 parameter to mmap is okay. But on a
> > >   32-bit machine, a len parameter just a few bytes short of 4G, rounded
> > >   up to a page boundary and hitting zero then, is not okay. Return
> > >   failure in that case.
> > > ...
> > >  	/* Adjust size for rounding (on both ends). */
> > >  	size += pageoff;			/* low end... */
> > > -	size = (vm_size_t) round_page(size);	/* hi end */
> > > +	/* Check for rounding up to zero. */
> > > +	if (round_page(size) < size)
> > > +		return (EINVAL);
> > 
> > The mmap(2) manpage says that len==0 results in EINVAL, so the manpage
> > needs updating.
> 
> The man page doesn't say that only len == 0 results in EINVAL, so it is
> not incorrect.

https://github.com/freebsd/freebsd/blob/master/lib/libc/sys/mmap.2#L451-L455

Tons of error conditions listed, one of which is len==0.

Thanks,

-- 
Shawn Webb
Cofounder / Security Engineer
HardenedBSD

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