From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f198.google.com (mail-wr0-f198.google.com [209.85.128.198]) by kanga.kvack.org (Postfix) with ESMTP id 7F1816B0011 for ; Fri, 2 Mar 2018 14:45:07 -0500 (EST) Received: by mail-wr0-f198.google.com with SMTP id q15so6903720wra.22 for ; Fri, 02 Mar 2018 11:45:07 -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 t142sor618604wmt.42.2018.03.02.11.45.05 for (Google Transport Security); Fri, 02 Mar 2018 11:45:05 -0800 (PST) From: Andrey Konovalov Subject: [RFC PATCH 05/14] khwasan: initialize shadow to 0xff Date: Fri, 2 Mar 2018 20:44:24 +0100 Message-Id: <85f426c1bbbff5b8a512c79c4a92055d1e7db1cd.1520017438.git.andreyknvl@google.com> In-Reply-To: References: In-Reply-To: References: Sender: owner-linux-mm@kvack.org List-ID: To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Jonathan Corbet , Catalin Marinas , Will Deacon , Theodore Ts'o , Jan Kara , Christopher Li , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Masahiro Yamada , Michal Marek , Mark Rutland , Ard Biesheuvel , Yury Norov , Nick Desaulniers , Marc Zyngier , Bob Picco , Suzuki K Poulose , Kristina Martsenko , Punit Agrawal , Dave Martin , James Morse , Julien Thierry , Michael Weiser , Steve Capper , Ingo Molnar , Thomas Gleixner , Sandipan Das , Paul Lawrence , David Woodhouse , Kees Cook , Geert Uytterhoeven , Josh Poimboeuf , Arnd Bergmann , kasan-dev@googlegroups.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ext4@vger.kernel.org, linux-sparse@vger.kernel.org, linux-mm@kvack.org, linux-kbuild@vger.kernel.org, Kostya Serebryany , Evgeniy Stepanov , Lee Smith , Ramana Radhakrishnan , Jacob Bramley , Ruben Ayrapetyan , Kees Cook , Jann Horn , Mark Brand Cc: Andrey Konovalov A KHWASAN shadow memory cell contains a memory tag, that corresponds to the tag in the top byte of the pointer, that points to that memory. The native top byte value of kernel pointers is 0xff, so with KHWASAN we need to initialize shadow memory to 0xff. This commit does that. --- arch/arm64/mm/kasan_init.c | 11 ++++++++++- include/linux/kasan.h | 8 ++++++++ mm/kasan/common.c | 7 +++++++ 3 files changed, 25 insertions(+), 1 deletion(-) diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c index dabfc1ecda3d..d4bceba60010 100644 --- a/arch/arm64/mm/kasan_init.c +++ b/arch/arm64/mm/kasan_init.c @@ -90,6 +90,10 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, do { phys_addr_t page_phys = early ? __pa_symbol(kasan_zero_page) : kasan_alloc_zeroed_page(node); +#if KASAN_SHADOW_INIT != 0 + if (!early) + memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); +#endif next = addr + PAGE_SIZE; set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); @@ -139,6 +143,11 @@ asmlinkage void __init kasan_early_init(void) KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT))); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE)); BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE)); + +#if KASAN_SHADOW_INIT != 0 + memset(kasan_zero_page, KASAN_SHADOW_INIT, PAGE_SIZE); +#endif + kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true); } @@ -235,7 +244,7 @@ void __init kasan_init(void) set_pte(&kasan_zero_pte[i], pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO)); - memset(kasan_zero_page, 0, PAGE_SIZE); + memset(kasan_zero_page, KASAN_SHADOW_INIT, PAGE_SIZE); cpu_replace_ttbr1(lm_alias(swapper_pg_dir)); /* At this point kasan is fully initialized. Enable error messages */ diff --git a/include/linux/kasan.h b/include/linux/kasan.h index 3c45e273a936..c34f413b0eac 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -139,6 +139,8 @@ static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; } #ifdef CONFIG_KASAN_CLASSIC +#define KASAN_SHADOW_INIT 0 + void kasan_cache_shrink(struct kmem_cache *cache); void kasan_cache_shutdown(struct kmem_cache *cache); @@ -149,4 +151,10 @@ static inline void kasan_cache_shutdown(struct kmem_cache *cache) {} #endif /* CONFIG_KASAN_CLASSIC */ +#ifdef CONFIG_KASAN_TAGS + +#define KASAN_SHADOW_INIT 0xff + +#endif /* CONFIG_KASAN_TAGS */ + #endif /* LINUX_KASAN_H */ diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 08f6c8cb9f84..f4ccb9425655 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -253,6 +253,9 @@ int kasan_module_alloc(void *addr, size_t size) __builtin_return_address(0)); if (ret) { +#if KASAN_SHADOW_INIT != 0 + __memset(ret, KASAN_SHADOW_INIT, shadow_size); +#endif find_vm_area(addr)->flags |= VM_KASAN; kmemleak_ignore(ret); return 0; @@ -297,6 +300,10 @@ static int __meminit kasan_mem_notifier(struct notifier_block *nb, if (!ret) return NOTIFY_BAD; +#if KASAN_SHADOW_INIT != 0 + __memset(ret, KASAN_SHADOW_INIT, shadow_end - shadow_start); +#endif + kmemleak_ignore(ret); return NOTIFY_OK; } -- 2.16.2.395.g2e18187dfd-goog -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org