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 17BF36B1B90 for ; Mon, 19 Nov 2018 12:27:21 -0500 (EST) Received: by mail-wr1-f72.google.com with SMTP id d11so30251864wrq.18 for ; Mon, 19 Nov 2018 09:27:21 -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 g18sor1811229wrw.3.2018.11.19.09.27.19 for (Google Transport Security); Mon, 19 Nov 2018 09:27:19 -0800 (PST) From: Andrey Konovalov Subject: [PATCH v11 15/24] kasan, mm: perform untagged pointers comparison in krealloc Date: Mon, 19 Nov 2018 18:26:31 +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 The krealloc function checks where the same buffer was reused or a new one allocated by comparing kernel pointers. Tag-based KASAN changes memory tag on the krealloc'ed chunk of memory and therefore also changes the pointer tag of the returned pointer. Therefore we need to perform comparison on untagged (with tags reset) pointers to check whether it's the same memory region or not. Reviewed-by: Andrey Ryabinin Reviewed-by: Dmitry Vyukov Signed-off-by: Andrey Konovalov --- mm/slab_common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slab_common.c b/mm/slab_common.c index 5f3504e26d4c..5aabcbd32d82 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1534,7 +1534,7 @@ void *krealloc(const void *p, size_t new_size, gfp_t flags) } ret = __do_krealloc(p, new_size, flags); - if (ret && p != ret) + if (ret && kasan_reset_tag(p) != kasan_reset_tag(ret)) kfree(p); return ret; -- 2.19.1.1215.g8438c0b245-goog