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Message-Id: <1065732315ef4e141b6177d8f612232d4d5bc0ab.1703188911.git.andreyknvl@google.com>
Date: Thu, 21 Dec 2023 21:04:48 +0100
From: andrey.konovalov@...ux.dev
To: Marco Elver <elver@...gle.com>
Cc: Andrey Konovalov <andreyknvl@...il.com>,
Alexander Potapenko <glider@...gle.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
kasan-dev@...glegroups.com,
Andrew Morton <akpm@...ux-foundation.org>,
linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH mm 06/11] kasan: clean up is_kfence_address checks
From: Andrey Konovalov <andreyknvl@...gle.com>
1. Do not untag addresses that are passed to is_kfence_address: it
tolerates tagged addresses.
2. Move is_kfence_address checks from internal KASAN functions
(kasan_poison/unpoison, etc.) to external-facing ones.
Note that kasan_poison/unpoison are never called outside of KASAN/slab
code anymore; the comment is wrong, so drop it.
3. Simplify/reorganize the code around the updated checks.
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
mm/kasan/common.c | 26 +++++++++++++++++---------
mm/kasan/kasan.h | 16 ++--------------
mm/kasan/shadow.c | 12 ------------
3 files changed, 19 insertions(+), 35 deletions(-)
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index f4255e807b74..86adf80cc11a 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -79,6 +79,9 @@ EXPORT_SYMBOL(kasan_disable_current);
void __kasan_unpoison_range(const void *address, size_t size)
{
+ if (is_kfence_address(address))
+ return;
+
kasan_unpoison(address, size, false);
}
@@ -218,9 +221,6 @@ static inline bool poison_slab_object(struct kmem_cache *cache, void *object,
tagged_object = object;
object = kasan_reset_tag(object);
- if (is_kfence_address(object))
- return false;
-
if (unlikely(nearest_obj(cache, virt_to_slab(object), object) != object)) {
kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_INVALID_FREE);
return true;
@@ -247,7 +247,12 @@ static inline bool poison_slab_object(struct kmem_cache *cache, void *object,
bool __kasan_slab_free(struct kmem_cache *cache, void *object,
unsigned long ip, bool init)
{
- bool buggy_object = poison_slab_object(cache, object, ip, init);
+ bool buggy_object;
+
+ if (is_kfence_address(object))
+ return false;
+
+ buggy_object = poison_slab_object(cache, object, ip, init);
return buggy_object ? true : kasan_quarantine_put(cache, object);
}
@@ -359,7 +364,7 @@ void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object
if (unlikely(object == NULL))
return NULL;
- if (is_kfence_address(kasan_reset_tag(object)))
+ if (is_kfence_address(object))
return (void *)object;
/* The object has already been unpoisoned by kasan_slab_alloc(). */
@@ -417,7 +422,7 @@ void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flag
if (unlikely(object == ZERO_SIZE_PTR))
return (void *)object;
- if (is_kfence_address(kasan_reset_tag(object)))
+ if (is_kfence_address(object))
return (void *)object;
/*
@@ -483,6 +488,9 @@ bool __kasan_mempool_poison_object(void *ptr, unsigned long ip)
return true;
}
+ if (is_kfence_address(ptr))
+ return false;
+
slab = folio_slab(folio);
return !poison_slab_object(slab->slab_cache, ptr, ip, false);
}
@@ -492,9 +500,6 @@ void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip)
struct slab *slab;
gfp_t flags = 0; /* Might be executing under a lock. */
- if (is_kfence_address(kasan_reset_tag(ptr)))
- return;
-
slab = virt_to_slab(ptr);
/*
@@ -507,6 +512,9 @@ void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip)
return;
}
+ if (is_kfence_address(ptr))
+ return;
+
/* Unpoison the object and save alloc info for non-kmalloc() allocations. */
unpoison_slab_object(slab->slab_cache, ptr, size, flags);
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 1c34511090d7..5fbcc1b805bc 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -466,35 +466,23 @@ static inline u8 kasan_random_tag(void) { return 0; }
static inline void kasan_poison(const void *addr, size_t size, u8 value, bool init)
{
- addr = kasan_reset_tag(addr);
-
- /* Skip KFENCE memory if called explicitly outside of sl*b. */
- if (is_kfence_address(addr))
- return;
-
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
if (WARN_ON(size & KASAN_GRANULE_MASK))
return;
- hw_set_mem_tag_range((void *)addr, size, value, init);
+ hw_set_mem_tag_range(kasan_reset_tag(addr), size, value, init);
}
static inline void kasan_unpoison(const void *addr, size_t size, bool init)
{
u8 tag = get_tag(addr);
- addr = kasan_reset_tag(addr);
-
- /* Skip KFENCE memory if called explicitly outside of sl*b. */
- if (is_kfence_address(addr))
- return;
-
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
size = round_up(size, KASAN_GRANULE_SIZE);
- hw_set_mem_tag_range((void *)addr, size, tag, init);
+ hw_set_mem_tag_range(kasan_reset_tag(addr), size, tag, init);
}
static inline bool kasan_byte_accessible(const void *addr)
diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
index 0154d200be40..30625303d01a 100644
--- a/mm/kasan/shadow.c
+++ b/mm/kasan/shadow.c
@@ -135,10 +135,6 @@ void kasan_poison(const void *addr, size_t size, u8 value, bool init)
*/
addr = kasan_reset_tag(addr);
- /* Skip KFENCE memory if called explicitly outside of sl*b. */
- if (is_kfence_address(addr))
- return;
-
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
if (WARN_ON(size & KASAN_GRANULE_MASK))
@@ -175,14 +171,6 @@ void kasan_unpoison(const void *addr, size_t size, bool init)
*/
addr = kasan_reset_tag(addr);
- /*
- * 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(addr))
- return;
-
if (WARN_ON((unsigned long)addr & KASAN_GRANULE_MASK))
return;
--
2.25.1
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