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Fix the integer overflow problem in pmap_init() when the user PT map is 

allocated, as noticed by Chuck Cranor.  In addition to re-arranging
the assignment as suggested by Niklas Hallqvist, check to see if maxproc
is higher than the number of available user PTs.  If it is, lower maxproc
to that value, the rationale being that it's much more desirable to have
fork() return EAGAIN than to have your system wedge.

XXX note that root can still raise maxproc with sysctl(2) later.  It's
probably worth having further discussion about this issue, but until
everyone has time to think about it, this seems like an acceptable solution
for the time being.
This commit is contained in:
thorpej 1995-12-05 20:01:54 +00:00
parent c94210debc
commit 9c784e07c1
1 changed files with 12 additions and 2 deletions
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14
sys/arch/hp300/hp300/pmap.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: pmap.c,v 1.22 1995/10/08 19:33:36 thorpej Exp $ */
/* $NetBSD: pmap.c,v 1.23 1995/12/05 20:01:54 thorpej Exp $ */
/*
* Copyright (c) 1991, 1993
@ -457,7 +457,17 @@ bogons:
* map where we want it.
*/
addr = HP_PTBASE;
s = min(HP_PTMAXSIZE, maxproc*HP_MAX_PTSIZE);
if ((HP_PTMAXSIZE / HP_MAX_PTSIZE) < maxproc) {
s = HP_PTMAXSIZE;
/*
* XXX We don't want to hang when we run out of
* page tables, so we lower maxproc so that fork()
* will fail instead. Note that root could still raise
* this value via sysctl(2).
*/
maxproc = (HP_PTMAXSIZE / HP_MAX_PTSIZE);
} else
s = (maxproc * HP_MAX_PTSIZE);
addr2 = addr + s;
rv = vm_map_find(kernel_map, NULL, 0, &addr, s, TRUE);
if (rv != KERN_SUCCESS)