From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm0-f70.google.com (mail-wm0-f70.google.com [74.125.82.70]) by kanga.kvack.org (Postfix) with ESMTP id 39BB16B026A for ; Thu, 9 Aug 2018 15:21:30 -0400 (EDT) Received: by mail-wm0-f70.google.com with SMTP id v24-v6so639473wmh.5 for ; Thu, 09 Aug 2018 12:21:30 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id h6-v6sor3109586wre.67.2018.08.09.12.21.28 for (Google Transport Security); Thu, 09 Aug 2018 12:21:28 -0700 (PDT) From: Andrey Konovalov Subject: [PATCH v5 08/18] khwasan: preassign tags to objects with ctors or SLAB_TYPESAFE_BY_RCU Date: Thu, 9 Aug 2018 21:21:00 +0200 Message-Id: <625d42d5cb7f20bb54ce7af2c4b87910b1474c74.1533842385.git.andreyknvl@google.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Catalin Marinas , Will Deacon , Christoph Lameter , Andrew Morton , Mark Rutland , Nick Desaulniers , Marc Zyngier , Dave Martin , Ard Biesheuvel , "Eric W . Biederman" , Ingo Molnar , Paul Lawrence , Geert Uytterhoeven , Arnd Bergmann , "Kirill A . Shutemov" , Greg Kroah-Hartman , Kate Stewart , Mike Rapoport , kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sparse@vger.kernel.org, linux-mm@kvack.org, linux-kbuild@vger.kernel.org Cc: Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Jann Horn , Mark Brand , Chintan Pandya , Vishwath Mohan , Andrey Konovalov An object constructor can initialize pointers within this objects based on the address of the object. Since the object address might be tagged, we need to assign a tag before calling constructor. The implemented approach is to assign tags to objects with constructors when a slab is allocated and call constructors once as usual. The downside is that such object would always have the same tag when it is reallocated, so we won't catch use-after-frees on it. Also pressign tags for objects from SLAB_TYPESAFE_BY_RCU caches, since they can be validy accessed after having been freed. Signed-off-by: Andrey Konovalov --- mm/slab.c | 6 +++++- mm/slub.c | 4 ++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/slab.c b/mm/slab.c index 6fdca9ec2ea4..3b4227059f2e 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -403,7 +403,11 @@ static inline struct kmem_cache *virt_to_cache(const void *obj) static inline void *index_to_obj(struct kmem_cache *cache, struct page *page, unsigned int idx) { - return page->s_mem + cache->size * idx; + void *obj; + + obj = page->s_mem + cache->size * idx; + obj = khwasan_preset_slab_tag(cache, idx, obj); + return obj; } /* diff --git a/mm/slub.c b/mm/slub.c index 8fa21afcd3fb..a891bc49dc38 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1532,12 +1532,14 @@ static bool shuffle_freelist(struct kmem_cache *s, struct page *page) /* First entry is used as the base of the freelist */ cur = next_freelist_entry(s, page, &pos, start, page_limit, freelist_count); + cur = khwasan_preset_slub_tag(s, cur); page->freelist = cur; for (idx = 1; idx < page->objects; idx++) { setup_object(s, page, cur); next = next_freelist_entry(s, page, &pos, start, page_limit, freelist_count); + next = khwasan_preset_slub_tag(s, next); set_freepointer(s, cur, next); cur = next; } @@ -1614,8 +1616,10 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) shuffle = shuffle_freelist(s, page); if (!shuffle) { + start = khwasan_preset_slub_tag(s, start); for_each_object_idx(p, idx, s, start, page->objects) { setup_object(s, page, p); + p = khwasan_preset_slub_tag(s, p); if (likely(idx < page->objects)) set_freepointer(s, p, p + s->size); else -- 2.18.0.597.ga71716f1ad-goog