From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id CB6336B026A for ; Fri, 25 May 2018 10:41:02 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id r23-v6so4403983wrc.2 for ; Fri, 25 May 2018 07:41:02 -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 n18-v6sor7335748wrm.29.2018.05.25.07.41.01 for (Google Transport Security); Fri, 25 May 2018 07:41:01 -0700 (PDT) From: Andrey Konovalov Subject: [PATCH v2 10/16] khwasan, mm: perform untagged pointers comparison in krealloc Date: Fri, 25 May 2018 16:40:26 +0200 Message-Id: <8ebe73c041d879639b1fb822578f247cccec91a6.1527259068.git.andreyknvl@google.com> 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 , Christopher Li , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Masahiro Yamada , Michal Marek , Andrey Konovalov , Mark Rutland , Nick Desaulniers , Yury Norov , Marc Zyngier , Kristina Martsenko , Suzuki K Poulose , Punit Agrawal , Dave Martin , Ard Biesheuvel , James Morse , Michael Weiser , Julien Thierry , Tyler Baicar , "Eric W . Biederman" , Thomas Gleixner , Ingo Molnar , Kees Cook , Sandipan Das , David Woodhouse , Paul Lawrence , Herbert Xu , Josh Poimboeuf , Geert Uytterhoeven , Tom Lendacky , Arnd Bergmann , Dan Williams , Michal Hocko , Jan Kara , Ross Zwisler , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , Matthew Wilcox , "Kirill A . Shutemov" , Souptick Joarder , Hugh Dickins , Davidlohr Bueso , Greg Kroah-Hartman , Philippe Ombredanne , Kate Stewart , Laura Abbott , Boris Brezillon , Vlastimil Babka , Pintu Agarwal , Doug Berger , Anshuman Khandual , Mike Rapoport , Mel Gorman , Pavel Tatashin , Tetsuo Handa , 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 , Kees Cook , Jann Horn , Mark Brand , Chintan Pandya The krealloc function checks where the same buffer was reused or a new one allocated by comparing kernel pointers. KHWASAN 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. 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 0582004351c4..451b094b8c5b 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1478,7 +1478,7 @@ 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 && khwasan_reset_tag(p) != khwasan_reset_tag(ret)) kfree(p); return ret; -- 2.17.0.921.gf22659ad46-goog