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@kernel.dk>

1 files changed, 1 insertions, 31 deletions

diff --git a/mm/slab.c b/mm/slab.c
index b1e40dafbab..6107f2380e0 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)
 {