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authorPekka Enberg <penberg@cs.helsinki.fi>2010-04-07 12:23:40 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-04-09 13:09:50 -0400
commitfc1c183353a113c71675fecd0485e5aa0fe68d72 (patch)
tree25fc50112c80402ab43bd86a3d6b6a99a0c3c128 /mm
parent4dc86ae1f925b2121d4e75058675895f83e54c71 (diff)
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')
-rw-r--r--mm/slab.c13
-rw-r--r--mm/util.c21
2 files changed, 22 insertions, 12 deletions
diff --git a/mm/slab.c b/mm/slab.c
index a9f325b28bed..bac0f4fcc216 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3602,21 +3602,10 @@ EXPORT_SYMBOL(kmem_cache_alloc_notrace);
3602 */ 3602 */
3603int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr) 3603int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr)
3604{ 3604{
3605 unsigned long addr = (unsigned long)ptr;
3606 unsigned long min_addr = PAGE_OFFSET;
3607 unsigned long align_mask = BYTES_PER_WORD - 1;
3608 unsigned long size = cachep->buffer_size; 3605 unsigned long size = cachep->buffer_size;
3609 struct page *page; 3606 struct page *page;
3610 3607
3611 if (unlikely(addr < min_addr)) 3608 if (unlikely(!kern_ptr_validate(ptr, size)))
3612 goto out;
3613 if (unlikely(addr > (unsigned long)high_memory - size))
3614 goto out;
3615 if (unlikely(addr & align_mask))
3616 goto out;
3617 if (unlikely(!kern_addr_valid(addr)))
3618 goto out;
3619 if (unlikely(!kern_addr_valid(addr + size - 1)))
3620 goto out; 3609 goto out;
3621 page = virt_to_page(ptr); 3610 page = virt_to_page(ptr);
3622 if (unlikely(!PageSlab(page))) 3611 if (unlikely(!PageSlab(page)))
diff --git a/mm/util.c b/mm/util.c
index 834db7be240f..f5712e8964be 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -186,6 +186,27 @@ void kzfree(const void *p)
186} 186}
187EXPORT_SYMBOL(kzfree); 187EXPORT_SYMBOL(kzfree);
188 188
189int kern_ptr_validate(const void *ptr, unsigned long size)
190{
191 unsigned long addr = (unsigned long)ptr;
192 unsigned long min_addr = PAGE_OFFSET;
193 unsigned long align_mask = sizeof(void *) - 1;
194
195 if (unlikely(addr < min_addr))
196 goto out;
197 if (unlikely(addr > (unsigned long)high_memory - size))
198 goto out;
199 if (unlikely(addr & align_mask))
200 goto out;
201 if (unlikely(!kern_addr_valid(addr)))
202 goto out;
203 if (unlikely(!kern_addr_valid(addr + size - 1)))
204 goto out;
205 return 1;
206out:
207 return 0;
208}
209
189/* 210/*
190 * strndup_user - duplicate an existing string from user space 211 * strndup_user - duplicate an existing string from user space
191 * @s: The string to duplicate 212 * @s: The string to duplicate