mm: introduce clear_highpage_kasan_tagged

commit d9da8f6cf55eeca642c021912af1890002464c64 upstream.

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: Andrey 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: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index 39bb9b47fa9cd4c633366f2097d5239a4323871e..7037c6bed55c0d11685a04f31e061db470d98ec0 100644 (file)
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -218,6 +218,16 @@ 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)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 135a081edb82c5c628589f295ad5f0fe98df07bb..a8bd356a4d1e3e3572033ccf5df17cbe720322fa 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1287,12 +1287,8 @@ static void kernel_init_free_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();
 }