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Date: Wed, 29 Aug 2018 13:35:12 +0200 From: Andrey Konovalov <andreyknvl@...gle.com> To: Andrey Ryabinin <aryabinin@...tuozzo.com>, Alexander Potapenko <glider@...gle.com>, Dmitry Vyukov <dvyukov@...gle.com>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will.deacon@....com>, Christoph Lameter <cl@...ux.com>, Andrew Morton <akpm@...ux-foundation.org>, Mark Rutland <mark.rutland@....com>, Nick Desaulniers <ndesaulniers@...gle.com>, Marc Zyngier <marc.zyngier@....com>, Dave Martin <dave.martin@....com>, Ard Biesheuvel <ard.biesheuvel@...aro.org>, "Eric W . Biederman" <ebiederm@...ssion.com>, Ingo Molnar <mingo@...nel.org>, Paul Lawrence <paullawrence@...gle.com>, Geert Uytterhoeven <geert@...ux-m68k.org>, Arnd Bergmann <arnd@...db.de>, "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Kate Stewart <kstewart@...uxfoundation.org>, Mike Rapoport <rppt@...ux.vnet.ibm.com>, kasan-dev@...glegroups.com, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, linux-sparse@...r.kernel.org, linux-mm@...ck.org, linux-kbuild@...r.kernel.org Cc: Kostya Serebryany <kcc@...gle.com>, Evgeniy Stepanov <eugenis@...gle.com>, Lee Smith <Lee.Smith@....com>, Ramana Radhakrishnan <Ramana.Radhakrishnan@....com>, Jacob Bramley <Jacob.Bramley@....com>, Ruben Ayrapetyan <Ruben.Ayrapetyan@....com>, Jann Horn <jannh@...gle.com>, Mark Brand <markbrand@...gle.com>, Chintan Pandya <cpandya@...eaurora.org>, Vishwath Mohan <vishwath@...gle.com>, Andrey Konovalov <andreyknvl@...gle.com> Subject: [PATCH v6 08/18] khwasan: preassign tags to objects with ctors or SLAB_TYPESAFE_BY_RCU 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 <andreyknvl@...gle.com> --- 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 4206e1b616e7..086d6558a6b6 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1531,12 +1531,14 @@ 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; } @@ -1613,8 +1615,10 @@ 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 -- 2.19.0.rc0.228.g281dcd1b4d0-goog
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