Commit d9da8f6c authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Andrew Morton
Browse files

mm: introduce clear_highpage_kasan_tagged 

Add a clear_highpage_kasan_tagged() helper that does clear_highpage() on a
page potentially tagged by KASAN.

This helper is used by the following patch.

Link: https://lkml.kernel.org/r/4471979b46b2c487787ddcd08b9dc5fedd1b6ffd.1654798516.git.andreyknvl@google.com


Signed-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent aeaec8e2

include/linux/highmem.h

+10 −0
Original line number Diff line number Diff line
@@ -243,6 +243,16 @@ static inline void clear_highpage(struct page *page) 
	kunmap_local(kaddr);

}



static inline void clear_highpage_kasan_tagged(struct page *page)

{

	u8 tag;



	tag = page_kasan_tag(page);

	page_kasan_tag_reset(page);

	clear_highpage(page);

	page_kasan_tag_set(page, tag);

}



#ifndef __HAVE_ARCH_TAG_CLEAR_HIGHPAGE



static inline void tag_clear_highpage(struct page *page)

mm/page_alloc.c

+2 −6
Original line number Diff line number Diff line
@@ -1302,12 +1302,8 @@ static void kernel_init_pages(struct page *page, int numpages) 


	/* s390's use of memset() could override KASAN redzones. */

	kasan_disable_current();

	for (i = 0; i < numpages; i++) {

		u8 tag = page_kasan_tag(page + i);

		page_kasan_tag_reset(page + i);

		clear_highpage(page + i);

		page_kasan_tag_set(page + i, tag);

	}

	for (i = 0; i < numpages; i++)

		clear_highpage_kasan_tagged(page + i);

	kasan_enable_current();

}