[PATCH RFC v2 19/21] kasan: don't round_up too much

From: Andrey Konovalov <andreyknvl@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>,
	 Vincenzo Frascino <vincenzo.frascino@arm.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	 Alexander Potapenko <glider@google.com>,
	Marco Elver <elver@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>,
	Kostya Serebryany <kcc@google.com>,
	 Peter Collingbourne <pcc@google.com>,
	Serban Constantinescu <serbanc@google.com>,
	 Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Elena Petrova <lenaptr@google.com>,
	 Branislav Rankov <Branislav.Rankov@arm.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	kasan-dev@googlegroups.com,
	 linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
	 linux-kernel@vger.kernel.org,
	Andrey Konovalov <andreyknvl@google.com>
Subject: [PATCH RFC v2 19/21] kasan: don't round_up too much
Date: Thu, 22 Oct 2020 15:19:11 +0200	[thread overview]
Message-ID: <f48f800933dacfc554d9094d864a01688abcbffd.1603372719.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1603372719.git.andreyknvl@google.com>

For tag-based mode kasan_poison_memory() already rounds up the size. Do
the same for software modes and remove round_up() from common code.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Link: https://linux-review.googlesource.com/id/Ib397128fac6eba874008662b4964d65352db4aa4
---
 mm/kasan/common.c | 8 ++------
 mm/kasan/shadow.c | 1 +
 2 files changed, 3 insertions(+), 6 deletions(-)

diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 5622b0ec0907..983383ebe32a 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -215,9 +215,7 @@ void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
 
 void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
 {
-	kasan_poison_memory(object,
-			round_up(cache->object_size, KASAN_GRANULE_SIZE),
-			KASAN_KMALLOC_REDZONE);
+	kasan_poison_memory(object, cache->object_size, KASAN_KMALLOC_REDZONE);
 }
 
 /*
@@ -290,7 +288,6 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
 {
 	u8 tag;
 	void *tagged_object;
-	unsigned long rounded_up_size;
 
 	tag = get_tag(object);
 	tagged_object = object;
@@ -311,8 +308,7 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
 		return true;
 	}
 
-	rounded_up_size = round_up(cache->object_size, KASAN_GRANULE_SIZE);
-	kasan_poison_memory(object, rounded_up_size, KASAN_KMALLOC_FREE);
+	kasan_poison_memory(object, cache->object_size, KASAN_KMALLOC_FREE);
 
 	if (static_branch_unlikely(&kasan_stack)) {
 		if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) ||
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 616ac64c4a21..ab1d39c566b9 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -82,6 +82,7 @@ void kasan_poison_memory(const void *address, size_t size, u8 value)
 	 * addresses to this function.
 	 */
 	address = reset_tag(address);
+	size = round_up(size, KASAN_GRANULE_SIZE);
 
 	shadow_start = kasan_mem_to_shadow(address);
 	shadow_end = kasan_mem_to_shadow(address + size);
-- 
2.29.0.rc1.297.gfa9743e501-goog


