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authorPekka Enberg <penberg@cs.helsinki.fi>2010-04-07 19:23:40 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2010-04-09 10:09:50 -0700
commitfc1c183353a113c71675fecd0485e5aa0fe68d72 (patch)
tree25fc50112c80402ab43bd86a3d6b6a99a0c3c128 /mm/util.c
parent4dc86ae1f925b2121d4e75058675895f83e54c71 (diff)
downloadlinux-fc1c183353a113c71675fecd0485e5aa0fe68d72.tar.gz
slab: Generify kernel pointer validation
As suggested by Linus, introduce a kern_ptr_validate() helper that does some sanity checks to make sure a pointer is a valid kernel pointer. This is a preparational step for fixing SLUB kmem_ptr_validate(). Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Matt Mackall <mpm@selenic.com> Cc: Nick Piggin <npiggin@suse.de> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/util.c')
-rw-r--r--mm/util.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/mm/util.c b/mm/util.c
index 834db7be240..f5712e8964b 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -186,6 +186,27 @@ void kzfree(const void *p)
}
EXPORT_SYMBOL(kzfree);
+int kern_ptr_validate(const void *ptr, unsigned long size)
+{
+ unsigned long addr = (unsigned long)ptr;
+ unsigned long min_addr = PAGE_OFFSET;
+ unsigned long align_mask = sizeof(void *) - 1;
+
+ if (unlikely(addr < min_addr))
+ goto out;
+ if (unlikely(addr > (unsigned long)high_memory - size))
+ goto out;
+ if (unlikely(addr & align_mask))
+ goto out;
+ if (unlikely(!kern_addr_valid(addr)))
+ goto out;
+ if (unlikely(!kern_addr_valid(addr + size - 1)))
+ goto out;
+ return 1;
+out:
+ return 0;
+}
+
/*
* strndup_user - duplicate an existing string from user space
* @s: The string to duplicate