kasan: clean up and rename ____kasan_kmalloc

Introduce a new poison_kmalloc_redzone helper function that poisons the
redzone for kmalloc object.

Drop the confusingly named ____kasan_kmalloc function and instead use
poison_kmalloc_redzone along with the other required parts of
____kasan_kmalloc in the callers' code.

This is a preparatory change for the following patches in this series.

Link: https://lkml.kernel.org/r/5881232ad357ec0d59a5b1aefd9e0673a386399a.1703024586.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Lobakin <alobakin@pm.me>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 59146886e57de46e1564c4ec99bc29265f544bcb..1217b260abc376533b59abf8c180563b3519c663 100644 (file)
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -312,26 +312,12 @@ void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
        return tagged_object;
 }
 
-static inline void *____kasan_kmalloc(struct kmem_cache *cache,
+static inline void poison_kmalloc_redzone(struct kmem_cache *cache,
                                const void *object, size_t size, gfp_t flags)
 {
        unsigned long redzone_start;
        unsigned long redzone_end;
 
-       if (gfpflags_allow_blocking(flags))
-               kasan_quarantine_reduce();
-
-       if (unlikely(object == NULL))
-               return NULL;
-
-       if (is_kfence_address(kasan_reset_tag(object)))
-               return (void *)object;
-
-       /*
-        * The object has already been unpoisoned by kasan_slab_alloc() for
-        * kmalloc() or by kasan_krealloc() for krealloc().
-        */
-
        /*
         * The redzone has byte-level precision for the generic mode.
         * Partially poison the last object granule to cover the unaligned
@@ -355,14 +341,25 @@ static inline void *____kasan_kmalloc(struct kmem_cache *cache,
        if (kasan_stack_collection_enabled() && is_kmalloc_cache(cache))
                kasan_save_alloc_info(cache, (void *)object, flags);
 
-       /* Keep the tag that was set by kasan_slab_alloc(). */
-       return (void *)object;
 }
 
 void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object,
                                        size_t size, gfp_t flags)
 {
-       return ____kasan_kmalloc(cache, object, size, flags);
+       if (gfpflags_allow_blocking(flags))
+               kasan_quarantine_reduce();
+
+       if (unlikely(object == NULL))
+               return NULL;
+
+       if (is_kfence_address(kasan_reset_tag(object)))
+               return (void *)object;
+
+       /* The object has already been unpoisoned by kasan_slab_alloc(). */
+       poison_kmalloc_redzone(cache, object, size, flags);
+
+       /* Keep the tag that was set by kasan_slab_alloc(). */
+       return (void *)object;
 }
 EXPORT_SYMBOL(__kasan_kmalloc);
 
@@ -408,6 +405,9 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag
        if (unlikely(object == ZERO_SIZE_PTR))
                return (void *)object;
 
+       if (is_kfence_address(kasan_reset_tag(object)))
+               return (void *)object;
+
        /*
         * Unpoison the object's data.
         * Part of it might already have been unpoisoned, but it's unknown
@@ -420,8 +420,10 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag
        /* Piggy-back on kmalloc() instrumentation to poison the redzone. */
        if (unlikely(!slab))
                return __kasan_kmalloc_large(object, size, flags);
-       else
-               return ____kasan_kmalloc(slab->slab_cache, object, size, flags);
+       else {
+               poison_kmalloc_redzone(slab->slab_cache, object, size, flags);
+               return (void *)object;
+       }
 }
 
 bool __kasan_mempool_poison_pages(struct page *page, unsigned int order,