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d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=VsAI4kIskvc7OgbGXOlaJf5U20hpa/63jMpnaocWLWM=; b=Z7thVLdjeUZqustSCAHaOQqb0H46UcvBZJDOxzU/C+BZIk8XFpxeBz/m7O7hYFC8ak f/Q9L0ehg5KV0mX8PnR35Ax/KiEg/m7XQKiFwbuRokweBzPA+EtYA7G4UIvwDESrtgj2 qY3pL35VuYMa4IZf0Tj40ICSWiwFIEbIUdy8pNuV0WI7eUoHVNJ1yM/MCWhRJml6v/I0 BesFpdCEX/xuh91qfjFwKQ6+6Ejnxt4hRC4xFmPJHKLBKijk/9lhY+4bzu/lyawpSw4l T86eP1+L+uVgZqnH+4Fg4kudKr43CUvFET69PJz4izRUTmnMS6fFDyWGnluKCh2mXcss i/aw== X-Gm-Message-State: AOAM530/pY4JXZyOh17W7PvHvs9WVHN8kX/Xs6BzRru7i9Kb4La5pD2/ n+g+mkL4Z5+ES6TEg6hX7D8kQHTHlY3wT1MY X-Google-Smtp-Source: ABdhPJzQ44VzGDQGjD82W9CmwEaWld7rLNdT6Y1+lJuUYaoCWdvd/M8e9RFhUQ1m43P7Ba8CtJwX2RPN19SUuUND X-Received: from andreyknvl3.muc.corp.google.com ([2a00:79e0:15:13:7220:84ff:fe09:7e9d]) (user=andreyknvl job=sendgmr) by 2002:a0c:eac4:: with SMTP id y4mr1106877qvp.19.1606162126939; Mon, 23 Nov 2020 12:08:46 -0800 (PST) Date: Mon, 23 Nov 2020 21:07:36 +0100 In-Reply-To: Message-Id: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.29.2.454.gaff20da3a2-goog Subject: [PATCH mm v11 12/42] kasan: hide invalid free check implementation From: Andrey Konovalov To: Andrew Morton Cc: Catalin Marinas , Will Deacon , Vincenzo Frascino , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 Signed-off-by: Vincenzo Frascino Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko --- 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 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 754217c258a8..67642acafe92 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) \ { \