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Date: Sat, 27 Nov 2010 20:44:33 +1100
From: Nick Piggin <npiggin@...nel.dk>
To: linux-fsdevel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH 03/46] kernel: kmem_ptr_validate considered harmful
This is a nasty and error prone API. It is no longer used, remove it.
Signed-off-by: Nick Piggin <npiggin@...nel.dk>
---
include/linux/slab.h | 2 --
mm/slab.c | 32 +-------------------------------
mm/slob.c | 5 -----
mm/slub.c | 40 ----------------------------------------
mm/util.c | 21 ---------------------
5 files changed, 1 insertions(+), 99 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 59260e2..fa90866 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -106,8 +106,6 @@ int kmem_cache_shrink(struct kmem_cache *);
void kmem_cache_free(struct kmem_cache *, void *);
unsigned int kmem_cache_size(struct kmem_cache *);
const char *kmem_cache_name(struct kmem_cache *);
-int kern_ptr_validate(const void *ptr, unsigned long size);
-int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr);
/*
* Please use this macro to create slab caches. Simply specify the
diff --git a/mm/slab.c b/mm/slab.c
index b1e40da..6107f23 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2781,7 +2781,7 @@ static void slab_put_obj(struct kmem_cache *cachep, struct slab *slabp,
/*
* Map pages beginning at addr to the given cache and slab. This is required
* for the slab allocator to be able to lookup the cache and slab of a
- * virtual address for kfree, ksize, kmem_ptr_validate, and slab debugging.
+ * virtual address for kfree, ksize, and slab debugging.
*/
static void slab_map_pages(struct kmem_cache *cache, struct slab *slab,
void *addr)
@@ -3660,36 +3660,6 @@ void *kmem_cache_alloc_notrace(struct kmem_cache *cachep, gfp_t flags)
EXPORT_SYMBOL(kmem_cache_alloc_notrace);
#endif
-/**
- * kmem_ptr_validate - check if an untrusted pointer might be a slab entry.
- * @cachep: the cache we're checking against
- * @ptr: pointer to validate
- *
- * This verifies that the untrusted pointer looks sane;
- * it is _not_ a guarantee that the pointer is actually
- * part of the slab cache in question, but it at least
- * validates that the pointer can be dereferenced and
- * looks half-way sane.
- *
- * Currently only used for dentry validation.
- */
-int kmem_ptr_validate(struct kmem_cache *cachep, const void *ptr)
-{
- unsigned long size = cachep->buffer_size;
- struct page *page;
-
- if (unlikely(!kern_ptr_validate(ptr, size)))
- goto out;
- page = virt_to_page(ptr);
- if (unlikely(!PageSlab(page)))
- goto out;
- if (unlikely(page_get_cache(page) != cachep))
- goto out;
- return 1;
-out:
- return 0;
-}
-
#ifdef CONFIG_NUMA
void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
{
diff --git a/mm/slob.c b/mm/slob.c
index 617b6d6..3588eaa 100644
--- a/mm/slob.c
+++ b/mm/slob.c
@@ -678,11 +678,6 @@ int kmem_cache_shrink(struct kmem_cache *d)
}
EXPORT_SYMBOL(kmem_cache_shrink);
-int kmem_ptr_validate(struct kmem_cache *a, const void *b)
-{
- return 0;
-}
-
static unsigned int slob_ready __read_mostly;
int slab_is_available(void)
diff --git a/mm/slub.c b/mm/slub.c
index 981fb73..5ed0941 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1917,17 +1917,6 @@ void kmem_cache_free(struct kmem_cache *s, void *x)
}
EXPORT_SYMBOL(kmem_cache_free);
-/* Figure out on which slab page the object resides */
-static struct page *get_object_page(const void *x)
-{
- struct page *page = virt_to_head_page(x);
-
- if (!PageSlab(page))
- return NULL;
-
- return page;
-}
-
/*
* Object placement in a slab is made very easy because we always start at
* offset 0. If we tune the size of the object to the alignment then we can
@@ -2386,35 +2375,6 @@ error:
}
/*
- * Check if a given pointer is valid
- */
-int kmem_ptr_validate(struct kmem_cache *s, const void *object)
-{
- struct page *page;
-
- if (!kern_ptr_validate(object, s->size))
- return 0;
-
- page = get_object_page(object);
-
- if (!page || s != page->slab)
- /* No slab or wrong slab */
- return 0;
-
- if (!check_valid_pointer(s, page, object))
- return 0;
-
- /*
- * We could also check if the object is on the slabs freelist.
- * But this would be too expensive and it seems that the main
- * purpose of kmem_ptr_valid() is to check if the object belongs
- * to a certain slab.
- */
- return 1;
-}
-EXPORT_SYMBOL(kmem_ptr_validate);
-
-/*
* Determine the size of a slab object
*/
unsigned int kmem_cache_size(struct kmem_cache *s)
diff --git a/mm/util.c b/mm/util.c
index 73dac81..f126975 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -186,27 +186,6 @@ 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
--
1.7.1
--
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