Re: don't let mmap allocate down to zero

[William Lee Irwin III <wli@holomorphy.com>]

On Thu, 27 Jan 2005, William Lee Irwin III wrote:
>> (b) sys_mremap() isn't covered.

On Thu, Jan 27, 2005 at 03:58:12PM -0500, Rik van Riel wrote:
> AFAICS it is covered.
> >--- mm1-2.6.11-rc2.orig/mm/mremap.c	2005-01-26 00:26:43.000000000 -0800
> >+++ mm1-2.6.11-rc2/mm/mremap.c	2005-01-27 12:34:34.000000000 -0800
> >@@ -297,6 +297,8 @@
> >	if (flags & MREMAP_FIXED) {
> >		if (new_addr & ~PAGE_MASK)
> >			goto out;
> >+		if (!new_addr)
> >+			goto out;
> 
> This looks broken, look at the MREMAP_FIXED part...

The only way I can make sense of this is if you're trying to say that
because the user is trying to pass in a fixed address, that 0 should
then be permitted.

The intention was to disallow vmas starting at 0 categorically. i.e. it
is very intentional to deny the MREMAP_FIXED to 0 case of mremap().
It was also the intention to deny the MAP_FIXED to 0 case of mmap(),
though I didn't actually sweep that much (if at all).


-- wli