From 233bd5b929aebf1dbddaf538eacbf0e084daf388 Mon Sep 17 00:00:00 2001
From: Andrew Morton <akpm@linux-foundation.org>
Date: Thu, 31 Dec 2020 22:04:37 +0000
Subject: [PATCH] revert kasan-remove-kfence-leftovers

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/kasan/kasan.h  |  9 +++++++++
 mm/kasan/shadow.c | 13 +++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index cc4d9e1d49b1..725a472e8ea7 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -3,6 +3,7 @@
 #define __MM_KASAN_KASAN_H
 
 #include <linux/kasan.h>
+#include <linux/kfence.h>
 #include <linux/stackdepot.h>
 
 #ifdef CONFIG_KASAN_HW_TAGS
@@ -304,12 +305,20 @@ static inline u8 random_tag(void) { return 0; }
 
 static inline void poison_range(const void *address, size_t size, u8 value)
 {
+	/* Skip KFENCE memory if called explicitly outside of sl*b. */
+	if (is_kfence_address(address))
+		return;
+
 	hw_set_mem_tag_range(kasan_reset_tag(address),
 			round_up(size, KASAN_GRANULE_SIZE), value);
 }
 
 static inline void unpoison_range(const void *address, size_t size)
 {
+	/* Skip KFENCE memory if called explicitly outside of sl*b. */
+	if (is_kfence_address(address))
+		return;
+
 	hw_set_mem_tag_range(kasan_reset_tag(address),
 			round_up(size, KASAN_GRANULE_SIZE), get_tag(address));
 }
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 7c2c08c55f32..e9efe88f7679 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -13,6 +13,7 @@
 #include <linux/init.h>
 #include <linux/kasan.h>
 #include <linux/kernel.h>
+#include <linux/kfence.h>
 #include <linux/kmemleak.h>
 #include <linux/memory.h>
 #include <linux/mm.h>
@@ -84,6 +85,10 @@ void poison_range(const void *address, size_t size, u8 value)
 	address = kasan_reset_tag(address);
 	size = round_up(size, KASAN_GRANULE_SIZE);
 
+	/* Skip KFENCE memory if called explicitly outside of sl*b. */
+	if (is_kfence_address(address))
+		return;
+
 	shadow_start = kasan_mem_to_shadow(address);
 	shadow_end = kasan_mem_to_shadow(address + size);
 
@@ -101,6 +106,14 @@ void unpoison_range(const void *address, size_t size)
 	 */
 	address = kasan_reset_tag(address);
 
+	/*
+	 * Skip KFENCE memory if called explicitly outside of sl*b. Also note
+	 * that calls to ksize(), where size is not a multiple of machine-word
+	 * size, would otherwise poison the invalid portion of the word.
+	 */
+	if (is_kfence_address(address))
+		return;
+
 	poison_range(address, size, tag);
 
 	if (size & KASAN_GRANULE_MASK) {
-- 
2.50.1