>Number:         1125
>Category:       kern
>Synopsis:       `exec'ing ZMAGIC executables whose data size is not page-aligned
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    kern-bug-people (Kernel Bug People)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jun  7 22:20:01 1995
>Originator:     Scott L. Burson
>Organization:
	ZETA-SOFT, Ltd.
>Release:        NetBSD-current circa 5/20/95
>Environment:
	NetBSD/sparc
System: NetBSD ganesh.zeta-soft.com 1.0A NetBSD 1.0A (GANESH) #17: Wed Jun 7 20:52:09 PDT 1995 gyro@ganesh.zeta-soft.com:/usr/src/sys/arch/sparc/compile/GANESH sparc


>Description:

I have some Franz Allegro Common Lisp executables I have been trying to run
under NetBSD-sparc.  They wouldn't start up; the problem turned out to be that
the data size in the a.out header was not page-aligned.  This bit in two ways:
first, `vm_mmap' failed in an obscure manner (with ENOMEM) if `size' was not
page-aligned.  I fixed this in the obvious way, and then the `vm_allocate'
call in `vmcmd_map_zero' blew out during the mapping of the BSS segment,
because it was trying to remap the first page of the segment (which was the
partial page at the end of the data segment).  I fixed this by modifying
`exec_aout_prep_zmagic' to be careful about this case.

An experienced kernel hacker should decide whether these are the right fixes.
In particular, one might argue that while the fix to `vm_mmap' may as well be
left in, as it doesn't look like it can do any harm, `exec_aout_prep_zmagic'
should be page-aligning all addresses and sizes in advance.

>How-To-Repeat:

See above.

>Fix:
*** vm/vm_mmap.c.~1~	Fri Mar 10 04:01:29 1995
--- vm/vm_mmap.c	Wed Jun  7 19:17:26 1995
***************
*** 679,684 ****
--- 679,685 ----
  
  	if (size == 0)
  		return (0);
+ 	size = round_page(size);		/* Gyro@zeta-soft.com 6/7/95 19:17 */
  
  	/* The file offset must be page aligned. */
  	if (foff & PAGE_MASK)
*** kern/exec_aout.c.~1~	Mon Nov 21 14:45:32 1994
--- kern/exec_aout.c	Wed Jun  7 20:40:03 1995
***************
*** 139,146 ****
  	    VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  
  	/* set up command for bss segment */
  	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, execp->a_bss,
! 	    epp->ep_daddr + execp->a_data, NULLVP, 0,
  	    VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  
  	return exec_aout_setup_stack(p, epp);
--- 139,149 ----
  	    VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  
  	/* set up command for bss segment */
+ 	/* `round_page' call inserted by Gyro@zeta-soft.com 6/7/95 20:38
+ 	 * If `execp->a_data' is not page aligned, we must be careful not to
+ 	 * overlap the region mapped for the data segment. */
  	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, execp->a_bss,
! 	    round_page(epp->ep_daddr + execp->a_data), NULLVP, 0,
  	    VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE);
  
  	return exec_aout_setup_stack(p, epp);

>Audit-Trail:
>Unformatted: