From: Andrey Konovalov <andreyknvl@google.com>
Date: Thu, 9 Jun 2022 18:18:46 +0000 (+0200)
Subject: mm: introduce clear_highpage_kasan_tagged
X-Git-Tag: v5.18.18~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=043fcdc2876029c45bf781a3f9ef31fc0b35e881;p=thirdparty%2Fkernel%2Fstable.git

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 39bb9b47fa9cd..7037c6bed55c0 100644
--- 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 135a081edb82c..a8bd356a4d1e3 100644
--- 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();
 }