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authorAndrey Konovalov <andreyknvl@google.com>2020-12-10 15:42:08 +1100
committerStephen Rothwell <sfr@canb.auug.org.au>2020-12-16 18:02:58 +1100
commit7149ff3bae9f0dac7c35bad846b3e0230fecc221 (patch)
treec57c5b7a3596bc78d9fe0cd74326c2790c117b63
parenta04c44b70367a41ec10339cc305e9f5120d7a6d9 (diff)
downloadlinux-7149ff3bae9f0dac7c35bad846b3e0230fecc221.tar.gz
kasan: hide invalid free check implementation
This is a preparatory commit for the upcoming addition of a new hardware tag-based (MTE-based) KASAN mode. For software KASAN modes the check is based on the value in the shadow memory. Hardware tag-based KASAN won't be using shadow, so hide the implementation of the check in check_invalid_free(). Also simplify the code for software tag-based mode. No functional changes for software modes. Link: https://lkml.kernel.org/r/d01534a4b977f97d87515dc590e6348e1406de81.1606161801.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Alexander Potapenko <glider@google.com> Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Branislav Rankov <Branislav.Rankov@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Kevin Brodsky <kevin.brodsky@arm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
-rw-r--r--mm/kasan/common.c19
-rw-r--r--mm/kasan/generic.c7
-rw-r--r--mm/kasan/kasan.h2
-rw-r--r--mm/kasan/sw_tags.c9
4 files changed, 19 insertions, 18 deletions
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index b3ebee6fcfca..ae55570b4d32 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -278,25 +278,9 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
return (void *)object;
}
-static inline bool shadow_invalid(u8 tag, s8 shadow_byte)
-{
- if (IS_ENABLED(CONFIG_KASAN_GENERIC))
- return shadow_byte < 0 ||
- shadow_byte >= KASAN_GRANULE_SIZE;
-
- /* else CONFIG_KASAN_SW_TAGS: */
- if ((u8)shadow_byte == KASAN_TAG_INVALID)
- return true;
- if ((tag != KASAN_TAG_KERNEL) && (tag != (u8)shadow_byte))
- return true;
-
- return false;
-}
-
static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
unsigned long ip, bool quarantine)
{
- s8 shadow_byte;
u8 tag;
void *tagged_object;
unsigned long rounded_up_size;
@@ -318,8 +302,7 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
return false;
- shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
- if (shadow_invalid(tag, shadow_byte)) {
+ if (check_invalid_free(tagged_object)) {
kasan_report_invalid_free(tagged_object, ip);
return true;
}
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 73f031d42db8..303b451131c2 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -188,6 +188,13 @@ bool check_memory_region(unsigned long addr, size_t size, bool write,
return check_memory_region_inline(addr, size, write, ret_ip);
}
+bool check_invalid_free(void *addr)
+{
+ s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
+
+ return shadow_byte < 0 || shadow_byte >= KASAN_GRANULE_SIZE;
+}
+
void kasan_cache_shrink(struct kmem_cache *cache)
{
quarantine_remove_cache(cache);
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index eec88bf28c64..e5b5f60bc963 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -166,6 +166,8 @@ void unpoison_range(const void *address, size_t size);
bool check_memory_region(unsigned long addr, size_t size, bool write,
unsigned long ret_ip);
+bool check_invalid_free(void *addr);
+
void *find_first_bad_addr(void *addr, size_t size);
const char *get_bug_type(struct kasan_access_info *info);
diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
index c0b3f327812b..64540109c461 100644
--- a/mm/kasan/sw_tags.c
+++ b/mm/kasan/sw_tags.c
@@ -121,6 +121,15 @@ bool check_memory_region(unsigned long addr, size_t size, bool write,
return true;
}
+bool check_invalid_free(void *addr)
+{
+ u8 tag = get_tag(addr);
+ u8 shadow_byte = READ_ONCE(*(u8 *)kasan_mem_to_shadow(reset_tag(addr)));
+
+ return (shadow_byte == KASAN_TAG_INVALID) ||
+ (tag != KASAN_TAG_KERNEL && tag != shadow_byte);
+}
+
#define DEFINE_HWASAN_LOAD_STORE(size) \
void __hwasan_load##size##_noabort(unsigned long addr) \
{ \