[PATCH v5 21/40] kasan: hide invalid free check implementation
flat view
STALE2164d
REVIEWED: 5 (5M)
From: Andrey Konovalov <hidden>
Date: 2020-10-12 20:45:54
Also in:
linux-mm, lkml
Subsystem:
kasan, memory management, the rest · Maintainers:
Andrey Ryabinin, Andrew Morton, Linus Torvalds
Revision v5 of 11 in this series; 1 review trailer.
Revisions (11)
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. Signed-off-by: Andrey Konovalov <redacted> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Marco Elver <elver@google.com> --- Change-Id: I5fae9531c9fc948eb4d4e0c589744032fc5a0789 --- mm/kasan/common.c | 19 +------------------ mm/kasan/generic.c | 7 +++++++ mm/kasan/kasan.h | 2 ++ mm/kasan/sw_tags.c | 9 +++++++++ 4 files changed, 19 insertions(+), 18 deletions(-)
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 123abfb760d4..543e6bf2168f 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c@@ -272,25 +272,9 @@ 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;
@@ -309,8 +293,7 @@ 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 ec4417156943..e1af3b6c53b8 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c@@ -187,6 +187,13 @@ 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 a2e71818d464..325bfd82bce4 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h@@ -164,6 +164,8 @@ void kasan_poison_memory(const void *address, size_t size, u8 value); 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 4bdd7dbd6647..b2638c2cd58a 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) \ { \
--
2.28.0.1011.ga647a8990f-goog
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