Re: [PATCH v1 15/16] khwasan, mm, arm64: tag non slab memory allocated via pagealloc

[Andrey Ryabinin <aryabinin@virtuozzo.com>]

On 05/08/2018 08:21 PM, Andrey Konovalov wrote:

> +#ifndef CONFIG_KASAN_HW
>  #define page_to_virt(page)	((void *)((__page_to_voff(page)) | PAGE_OFFSET))
> +#else
> +#define page_to_virt(page)	({					\
> +	unsigned long __addr =						\
> +		((__page_to_voff(page)) | PAGE_OFFSET);			\
> +	if (!PageSlab((struct page *)page))				\
> +		__addr = KASAN_SET_TAG(__addr, page_kasan_tag(page));	\

You could avoid 'if (!PageSlab())' check by adding page_kasan_tag_reset() into kasan_poison_slab().


> +	((void *)__addr);						\
> +})
> +#endif
> +
>  #define virt_to_page(vaddr)	((struct page *)((__virt_to_pgoff(vaddr)) | VMEMMAP_START))
>  
>  #define _virt_addr_valid(kaddr)	pfn_valid((((u64)(kaddr) & ~PAGE_OFFSET) \



> diff --git a/mm/cma.c b/mm/cma.c
> index aa40e6c7b042..f657db289bba 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -526,6 +526,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
>  	}
>  
>  	trace_cma_alloc(pfn, page, count, align);
> +	page_kasan_tag_reset(page);
  

Why? Comment needed.


>  	if (ret && !(gfp_mask & __GFP_NOWARN)) {
>  		pr_err("%s: alloc failed, req-size: %zu pages, ret: %d\n",
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 0654bf97257b..7cd4a4e8c3be 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -207,8 +207,18 @@ void kasan_unpoison_stack_above_sp_to(const void *watermark)
>  
>  void kasan_alloc_pages(struct page *page, unsigned int order)
>  {
> +#ifdef CONFIG_KASAN_GENERIC
>  	if (likely(!PageHighMem(page)))
>  		kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
> +#else
> +	if (!PageSlab(page)) {
> +		u8 tag = random_tag();
> +
> +		kasan_poison_shadow(page_address(page), PAGE_SIZE << order,
> +					tag);
> +		page_kasan_tag_set(page, tag);
> +	}
> +#endif
>  }


diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index b8e0a8215021..f9f2181164a2 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -207,18 +207,11 @@ void kasan_unpoison_stack_above_sp_to(const void *watermark)
 
 void kasan_alloc_pages(struct page *page, unsigned int order)
 {
-#ifdef CONFIG_KASAN_GENERIC
-	if (likely(!PageHighMem(page)))
-		kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
-#else
-	if (!PageSlab(page)) {
-		u8 tag = random_tag();
+	if (unlikely(PageHighMem(page)))
+		return;
 
-		kasan_poison_shadow(page_address(page), PAGE_SIZE << order,
-					tag);
-		page_kasan_tag_set(page, tag);
-	}
-#endif
+	page_kasan_tag_set(page, random_tag());
+	kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
 }
 
 void kasan_free_pages(struct page *page, unsigned int order)
-- 
2.16.1


>  
>  void kasan_free_pages(struct page *page, unsigned int order)
> @@ -433,6 +443,7 @@ void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
>  #else
>  	tag = random_tag();
>  	kasan_poison_shadow(ptr, redzone_start - (unsigned long)ptr, tag);
> +	page_kasan_tag_set(page, tag);

As already said before no changes needed in kasan_kmalloc_large. kasan_alloc_pages() alredy did tag_set().

>  #endif
>  	kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
>  		KASAN_PAGE_REDZONE);
> @@ -462,7 +473,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
>  	page = virt_to_head_page(ptr);
>  
>  	if (unlikely(!PageSlab(page))) {
> -		if (reset_tag(ptr) != page_address(page)) {
> +		if (ptr != page_address(page)) {
>  			kasan_report_invalid_free(ptr, ip);
>  			return;
>  		}
> @@ -475,7 +486,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
>  
>  void kasan_kfree_large(void *ptr, unsigned long ip)
>  {
> -	if (reset_tag(ptr) != page_address(virt_to_head_page(ptr)))
> +	if (ptr != page_address(virt_to_head_page(ptr)))
>  		kasan_report_invalid_free(ptr, ip);
>  	/* The object will be poisoned by page_alloc. */
>  }