From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by kanga.kvack.org (Postfix) with ESMTP id 409886B035D for ; Tue, 6 Nov 2018 12:31:00 -0500 (EST) Received: by mail-wr1-f72.google.com with SMTP id 37-v6so12407149wrb.15 for ; Tue, 06 Nov 2018 09:31:00 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id p127-v6sor1697443wmd.28.2018.11.06.09.30.58 for (Google Transport Security); Tue, 06 Nov 2018 09:30:58 -0800 (PST) From: Andrey Konovalov Subject: [PATCH v10 10/22] kasan: preassign tags to objects with ctors or SLAB_TYPESAFE_BY_RCU Date: Tue, 6 Nov 2018 18:30:25 +0100 Message-Id: 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. Reviewed-by: Andrey Ryabinin Reviewed-by: Dmitry Vyukov Signed-off-by: Andrey Konovalov --- mm/slab.c | 2 +- mm/slub.c | 24 ++++++++++++++---------- 2 files changed, 15 insertions(+), 11 deletions(-) diff --git a/mm/slab.c b/mm/slab.c index 26f60a22e5e0..27859fb39889 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2574,7 +2574,7 @@ static void cache_init_objs(struct kmem_cache *cachep, for (i = 0; i < cachep->num; i++) { objp = index_to_obj(cachep, page, i); - kasan_init_slab_obj(cachep, objp); + objp = kasan_init_slab_obj(cachep, objp); /* constructor could break poison info */ if (DEBUG == 0 && cachep->ctor) { diff --git a/mm/slub.c b/mm/slub.c index e739d46600b9..08740c3f3745 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1451,16 +1451,17 @@ static inline bool slab_free_freelist_hook(struct kmem_cache *s, #endif } -static void setup_object(struct kmem_cache *s, struct page *page, +static void *setup_object(struct kmem_cache *s, struct page *page, void *object) { setup_object_debug(s, page, object); - kasan_init_slab_obj(s, object); + object = kasan_init_slab_obj(s, object); if (unlikely(s->ctor)) { kasan_unpoison_object_data(s, object); s->ctor(object); kasan_poison_object_data(s, object); } + return object; } /* @@ -1568,16 +1569,16 @@ 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 = setup_object(s, page, 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 = setup_object(s, page, next); set_freepointer(s, cur, next); cur = next; } - setup_object(s, page, cur); set_freepointer(s, cur, NULL); return true; @@ -1599,7 +1600,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) struct page *page; struct kmem_cache_order_objects oo = s->oo; gfp_t alloc_gfp; - void *start, *p; + void *start, *p, *next; int idx, order; bool shuffle; @@ -1651,13 +1652,16 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) if (!shuffle) { for_each_object_idx(p, idx, s, start, page->objects) { - setup_object(s, page, p); - if (likely(idx < page->objects)) - set_freepointer(s, p, p + s->size); - else + if (likely(idx < page->objects)) { + next = p + s->size; + next = setup_object(s, page, next); + set_freepointer(s, p, next); + } else set_freepointer(s, p, NULL); } - page->freelist = fixup_red_left(s, start); + start = fixup_red_left(s, start); + start = setup_object(s, page, start); + page->freelist = start; } page->inuse = page->objects; -- 2.19.1.930.g4563a0d9d0-goog