Re: kern/50469: PaX ASLR breaks netbsd32 emulation

[Martin Husemann <martin%duskware.de@localhost>]

The following reply was made to PR kern/50469; it has been noted by GNATS.

From: Martin Husemann <martin%duskware.de@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/50469: PaX ASLR breaks netbsd32 emulation
Date: Wed, 25 Nov 2015 09:19:47 +0100

 On Wed, Nov 25, 2015 at 12:30:00AM +0000, Pierre Pronchery wrote:
 >  	size += pageoff;			/* add offset */
 >  	size = (vsize_t)round_page(size);	/* round up */
 >  
 > +#ifdef PAX_ASLR
 > +	pax_aslr(l, &addr, orig_addr, flags);
 > +#endif /* PAX_ASLR */
 
 You need to explain this a bit - the PAX_ASLR code is obfuscated (for
 example nxr can not even find the pax_aslr() definition).
 
 If you move the ASLR up this far, you may break addr == 0 handling further
 down?
 
 A better fix probably is to
 
  a) make the pax_aslr() call emulation specific
 
 or
 
  b) fix pax_aslr() to respect the the emulation specifics/VA settings of
     the passed lwp (including VM_MAP_TOPDOWN and the limits)
 
 
 Martin