From: Andrey Konovalov <andreyknvl@google.com>
To: Catalin Marinas <catalin.marinas@arm.com>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>,
Marco Elver <elver@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Will Deacon <will.deacon@arm.com>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Peter Collingbourne <pcc@google.com>,
Evgenii Stepanov <eugenis@google.com>,
Branislav Rankov <Branislav.Rankov@arm.com>,
Kevin Brodsky <kevin.brodsky@arm.com>,
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 08/12] kasan, mm: optimize krealloc poisoning
Date: Mon, 1 Feb 2021 20:43:32 +0100 [thread overview]
Message-ID: <431c6cfa0ac8fb2b33d7ab561a64aa84c844d1a0.1612208222.git.andreyknvl@google.com> (raw)
In-Reply-To: <cover.1612208222.git.andreyknvl@google.com>
Currently, krealloc() always calls ksize(), which unpoisons the whole
object including the redzone. This is inefficient, as kasan_krealloc()
repoisons the redzone for objects that fit into the same buffer.
This patch changes krealloc() instrumentation to use uninstrumented
__ksize() that doesn't unpoison the memory. Instead, kasan_kreallos()
is changed to unpoison the memory excluding the redzone.
For objects that don't fit into the old allocation, this patch disables
KASAN accessibility checks when copying memory into a new object instead
of unpoisoning it.
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
---
mm/kasan/common.c | 12 ++++++++++--
mm/slab_common.c | 20 ++++++++++++++------
2 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 9c64a00bbf9c..a51d6ea580b0 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -476,7 +476,7 @@ static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
/*
* The object has already been unpoisoned by kasan_slab_alloc() for
- * kmalloc() or by ksize() for krealloc().
+ * kmalloc() or by kasan_krealloc() for krealloc().
*/
/*
@@ -526,7 +526,7 @@ void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
/*
* The object has already been unpoisoned by kasan_alloc_pages() for
- * alloc_pages() or by ksize() for krealloc().
+ * alloc_pages() or by kasan_krealloc() for krealloc().
*/
/*
@@ -554,8 +554,16 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag
if (unlikely(object == ZERO_SIZE_PTR))
return (void *)object;
+ /*
+ * Unpoison the object's data.
+ * Part of it might already have been unpoisoned, but it's unknown
+ * how big that part is.
+ */
+ kasan_unpoison(object, size);
+
page = virt_to_head_page(object);
+ /* Piggy-back on kmalloc() instrumentation to poison the redzone. */
if (unlikely(!PageSlab(page)))
return __kasan_kmalloc_large(object, size, flags);
else
diff --git a/mm/slab_common.c b/mm/slab_common.c
index dad70239b54c..821f657d38b5 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1140,19 +1140,27 @@ static __always_inline void *__do_krealloc(const void *p, size_t new_size,
void *ret;
size_t ks;
- if (likely(!ZERO_OR_NULL_PTR(p)) && !kasan_check_byte(p))
- return NULL;
-
- ks = ksize(p);
+ /* Don't use instrumented ksize to allow precise KASAN poisoning. */
+ if (likely(!ZERO_OR_NULL_PTR(p))) {
+ if (!kasan_check_byte(p))
+ return NULL;
+ ks = __ksize(p);
+ } else
+ ks = 0;
+ /* If the object still fits, repoison it precisely. */
if (ks >= new_size) {
p = kasan_krealloc((void *)p, new_size, flags);
return (void *)p;
}
ret = kmalloc_track_caller(new_size, flags);
- if (ret && p)
- memcpy(ret, p, ks);
+ if (ret && p) {
+ /* Disable KASAN checks as the object's redzone is accessed. */
+ kasan_disable_current();
+ memcpy(ret, kasan_reset_tag(p), ks);
+ kasan_enable_current();
+ }
return ret;
}
--
2.30.0.365.g02bc693789-goog
next prev parent reply other threads:[~2021-02-01 19:47 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-01 19:43 [PATCH 00/12] kasan: optimizations and fixes for HW_TAGS Andrey Konovalov
2021-02-01 19:43 ` [PATCH 01/12] kasan, mm: don't save alloc stacks twice Andrey Konovalov
2021-02-02 16:06 ` Marco Elver
2021-02-02 18:01 ` Andrey Konovalov
2021-02-02 18:40 ` Marco Elver
2021-02-01 19:43 ` [PATCH 02/12] kasan, mm: optimize kmalloc poisoning Andrey Konovalov
2021-02-02 16:25 ` Marco Elver
2021-02-02 17:15 ` Andrey Konovalov
2021-02-02 17:39 ` Marco Elver
2021-02-01 19:43 ` [PATCH 03/12] kasan: optimize large " Andrey Konovalov
2021-02-02 16:57 ` Marco Elver
2021-02-01 19:43 ` [PATCH 04/12] kasan: clean up setting free info in kasan_slab_free Andrey Konovalov
2021-02-02 17:03 ` Marco Elver
2021-02-01 19:43 ` [PATCH 05/12] kasan: unify large kfree checks Andrey Konovalov
2021-02-03 12:13 ` Marco Elver
2021-02-01 19:43 ` [PATCH 06/12] kasan: rework krealloc tests Andrey Konovalov
2021-02-03 14:48 ` Marco Elver
2021-02-01 19:43 ` [PATCH 07/12] kasan, mm: remove krealloc side-effect Andrey Konovalov
2021-02-03 15:10 ` Marco Elver
2021-02-01 19:43 ` Andrey Konovalov [this message]
2021-02-03 14:34 ` [PATCH 08/12] kasan, mm: optimize krealloc poisoning Marco Elver
2021-02-01 19:43 ` [PATCH 09/12] kasan: ensure poisoning size alignment Andrey Konovalov
2021-02-03 15:31 ` Marco Elver
2021-02-01 19:43 ` [PATCH 10/12] arm64: kasan: simplify and inline MTE functions Andrey Konovalov
2021-02-01 22:44 ` Andrew Morton
2021-02-04 12:39 ` Vincenzo Frascino
2021-02-02 15:42 ` Catalin Marinas
2021-02-02 18:04 ` Andrey Konovalov
2021-02-04 12:37 ` Vincenzo Frascino
2021-02-01 19:43 ` [PATCH 11/12] kasan: always inline HW_TAGS helper functions Andrey Konovalov
2021-02-03 15:51 ` Marco Elver
2021-02-01 19:43 ` [PATCH 12/12] arm64: kasan: export MTE symbols for KASAN tests Andrey Konovalov
2021-02-02 10:46 ` Will Deacon
2021-02-02 13:42 ` Andrey Konovalov
2021-02-02 15:43 ` Catalin Marinas
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