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From: Alan Cox <alc@FreeBSD.org>
Date: Sat, 21 Jan 2012 08:26:41 +0000 (UTC)
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Subject: svn commit: r230421 - stable/9/sys/i386/include
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Author: alc
Date: Sat Jan 21 08:26:41 2012
New Revision: 230421
URL: http://svn.freebsd.org/changeset/base/230421

Log:
  MFC r228398
    Avoid the possibility of integer overflow in the calculation of
    VM_KMEM_SIZE_MAX.  Specifically, if the user/kernel address space split
    was changed such that the kernel address space was greater than or equal
    to 2 GB, then overflow would occur.
  
  PR:		161721

Modified:
  stable/9/sys/i386/include/vmparam.h
Directory Properties:
  stable/9/sys/   (props changed)
  stable/9/sys/amd64/include/xen/   (props changed)
  stable/9/sys/boot/   (props changed)
  stable/9/sys/boot/i386/efi/   (props changed)
  stable/9/sys/boot/ia64/efi/   (props changed)
  stable/9/sys/boot/ia64/ski/   (props changed)
  stable/9/sys/boot/powerpc/boot1.chrp/   (props changed)
  stable/9/sys/boot/powerpc/ofw/   (props changed)
  stable/9/sys/cddl/contrib/opensolaris/   (props changed)
  stable/9/sys/conf/   (props changed)
  stable/9/sys/contrib/dev/acpica/   (props changed)
  stable/9/sys/contrib/octeon-sdk/   (props changed)
  stable/9/sys/contrib/pf/   (props changed)
  stable/9/sys/contrib/x86emu/   (props changed)

Modified: stable/9/sys/i386/include/vmparam.h
==============================================================================
--- stable/9/sys/i386/include/vmparam.h	Sat Jan 21 07:57:27 2012	(r230420)
+++ stable/9/sys/i386/include/vmparam.h	Sat Jan 21 08:26:41 2012	(r230421)
@@ -186,11 +186,12 @@
 #endif
 
 /*
- * Ceiling on amount of kmem_map kva space.
+ * Ceiling on the amount of kmem_map KVA space: 40% of the entire KVA space
+ * rounded to the nearest multiple of the superpage size.
  */
 #ifndef VM_KMEM_SIZE_MAX
-#define	VM_KMEM_SIZE_MAX	((VM_MAX_KERNEL_ADDRESS - \
-    VM_MIN_KERNEL_ADDRESS) * 2 / 5)
+#define	VM_KMEM_SIZE_MAX	(((((VM_MAX_KERNEL_ADDRESS - \
+    VM_MIN_KERNEL_ADDRESS) >> (PDRSHIFT - 2)) + 5) / 10) << PDRSHIFT)
 #endif
 
 /* initial pagein size of beginning of executable file */