From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3818C43381 for ; Thu, 14 Feb 2019 00:25:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C3A38205F4 for ; Thu, 14 Feb 2019 00:25:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="HhlIJr4F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730636AbfBNAZy (ORCPT ); Wed, 13 Feb 2019 19:25:54 -0500 Received: from mail-wr1-f68.google.com ([209.85.221.68]:47071 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726250AbfBNAZx (ORCPT ); Wed, 13 Feb 2019 19:25:53 -0500 Received: by mail-wr1-f68.google.com with SMTP id l9so4516423wrt.13 for ; Wed, 13 Feb 2019 16:25:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=xv22CgztNiptmL1IpEe32/U9BVLPdU1sqDTM5ZydeiE=; b=HhlIJr4FWxNaNivefuJ+bnt6Cq6HW7Q52ilE48ZsQqjbtnHgee4hlqRgSCcjUyQ3d5 RBdZpO9q2BMCElpsu8MXwIzHOZe5OUT5V8X7obmacrhhCOGKhX8nOQwKazkEjSUND7xk 66AtVE3HBZnXxcev29ErJipHiWd3dzL/rEqAxab/+R7IAKEDZJ8thijXd9ztOjoHl/6C XDXL+vWafOandWWLJMbEb6N1SIHoCLHF4ZsxnBgIJ6z7DVSB23yvsjKxRmeC5yYH+a91 NrmImhn+jkl+ZXn5wJdNRaQrjaLJV9E0JojwqpVn7/1xHsCbw/mYOLRJqUsLR/pLYZu+ /9CA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=xv22CgztNiptmL1IpEe32/U9BVLPdU1sqDTM5ZydeiE=; b=qEqwxXmAvfgt/M1ngar/v+2Gs88rxO4fYO7ORtX5qOjIfu6cBgTstsSuntBKnEIzD0 YUkkatA2S4U0pUO4VL7ctyyOuHQW6fMDxaFRKGIreJKuNYQcRxPxfkMFa1eH3Tnb7Ct1 aH/iI7KHMCB3rVdfAg4cRPR0a4/Vc3fcFtSvXZLLi6zAOLivFb403ONi5cGP7mx3AsrW ZCilO11ID234/1c9MVdFJES9K3CR+0KFzqIk0zhhyzx8n7DsJDWu63oTT3dMOyO66S64 5nkLiu/24xJg3F33GbH9oTIvRO2aiqpCjA5I8vzNQbBEAvR9iJtPMhNThQUDtasc/IkW pKZQ== X-Gm-Message-State: AHQUAuYqNYRE0qs9cJBI1ojaxxsGsnjr0dtiiMHMZgJMffDJeHeKJL8g 8z2opymDHJwZh8KnVqt3k5AtNA== X-Google-Smtp-Source: AHgI3IYd9U0Z1ZibscRpnAuj8JVl1ut7OMIRHjvQVt/fMZsv+OV+uKxcoCfJmTEmRasdp0dHRvhurg== X-Received: by 2002:adf:9f54:: with SMTP id f20mr542834wrg.88.1550103951643; Wed, 13 Feb 2019 16:25:51 -0800 (PST) Received: from andreyknvl0.muc.corp.google.com ([2a00:79e0:15:13:8ce:d7fa:9f4c:492]) by smtp.gmail.com with ESMTPSA id b3sm1442324wme.27.2019.02.13.16.25.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Feb 2019 16:25:50 -0800 (PST) From: Andrey Konovalov To: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , Catalin Marinas , Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Qian Cai , Vincenzo Frascino , Kostya Serebryany , Evgeniy Stepanov , Andrey Konovalov Subject: [PATCH] kasan, slub: fix more conflicts with CONFIG_SLAB_FREELIST_HARDENED Date: Thu, 14 Feb 2019 01:25:47 +0100 Message-Id: X-Mailer: git-send-email 2.20.1.791.gb4d0f1c61a-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged. Normally, this doesn't cause any issues, as both set_freepointer() and get_freepointer() are called with a pointer with the same tag. However, there are some issues with CONFIG_SLUB_DEBUG code. For example, when __free_slub() iterates over objects in a cache, it passes untagged pointers to check_object(). check_object() in turns calls get_freepointer() with an untagged pointer, which causes the freepointer to be restored incorrectly. Add kasan_reset_tag to freelist_ptr(). Also add a detailed comment. Signed-off-by: Andrey Konovalov --- mm/slub.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 80da3a40b74d..c80e6699357c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -249,7 +249,18 @@ static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr, unsigned long ptr_addr) { #ifdef CONFIG_SLAB_FREELIST_HARDENED - return (void *)((unsigned long)ptr ^ s->random ^ ptr_addr); + /* + * When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged. + * Normally, this doesn't cause any issues, as both set_freepointer() + * and get_freepointer() are called with a pointer with the same tag. + * However, there are some issues with CONFIG_SLUB_DEBUG code. For + * example, when __free_slub() iterates over objects in a cache, it + * passes untagged pointers to check_object(). check_object() in turns + * calls get_freepointer() with an untagged pointer, which causes the + * freepointer to be restored incorrectly. + */ + return (void *)((unsigned long)ptr ^ s->random ^ + (unsigned long)kasan_reset_tag((void *)ptr_addr)); #else return ptr; #endif -- 2.20.1.791.gb4d0f1c61a-goog