Author: alc
Date: Wed Dec 7 07:03:14 2011
New Revision: 228317
URL: http://svn.freebsd.org/changeset/base/228317
Log:
Eliminate the possibility of 32-bit arithmetic overflow in the calculation
of vm_kmem_size that may occur if the system administrator has specified a
vm.vm_kmem_size tunable value that exceeds the hard cap.
PR: 162741
Submitted by: Adam McDougall
Reviewed by: bde@
MFC after: 3 weeks
Modified:
head/sys/kern/kern_malloc.c
Modified: head/sys/kern/kern_malloc.c
==============================================================================
--- head/sys/kern/kern_malloc.c Wed Dec 7 00:22:34 2011 (r228316)
+++ head/sys/kern/kern_malloc.c Wed Dec 7 07:03:14 2011 (r228317)
@@ -740,11 +740,11 @@ kmeminit(void *dummy)
/*
* Limit kmem virtual size to twice the physical memory.
* This allows for kmem map sparseness, but limits the size
- * to something sane. Be careful to not overflow the 32bit
- * ints while doing the check.
+ * to something sane. Be careful to not overflow the 32bit
+ * ints while doing the check or the adjustment.
*/
- if (((vm_kmem_size / 2) / PAGE_SIZE) > cnt.v_page_count)
- vm_kmem_size = 2 * cnt.v_page_count * PAGE_SIZE;
+ if (vm_kmem_size / 2 / PAGE_SIZE > mem_size)
+ vm_kmem_size = 2 * mem_size * PAGE_SIZE;
#ifdef DEBUG_MEMGUARD
tmp = memguard_fudge(vm_kmem_size, vm_kmem_size_max);
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