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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,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 5243DC433B4 for ; Fri, 14 May 2021 07:22:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 32C4961446 for ; Fri, 14 May 2021 07:22:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232542AbhENHXq (ORCPT ); Fri, 14 May 2021 03:23:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40910 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231331AbhENHXp (ORCPT ); Fri, 14 May 2021 03:23:45 -0400 Received: from mail-qk1-x74a.google.com (mail-qk1-x74a.google.com [IPv6:2607:f8b0:4864:20::74a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 57AFEC061574 for ; Fri, 14 May 2021 00:22:33 -0700 (PDT) Received: by mail-qk1-x74a.google.com with SMTP id d15-20020a05620a136fb02902e9e93c69c8so21228455qkl.23 for ; Fri, 14 May 2021 00:22:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=wrcmbdNNJFx//dV10zYXdyJfZ8i9iBUOXuvlPxh7U7s=; b=apLDegMhJMs8ZJ0Xs14xG/DWMAf8uNy5/PaHXqPiLM8OqurGbgN1sVeEbolRgi0/aG 0DawaeTh5ck+2X8Ylv+PY4v2330VfUWf6BPUkmj2ptIaD+Ol1DzXkgAW7Fp90P9ECPNE QAwsSYUmQjcMEcrqy3kP82OqM/N4PHuCoI4KWFl1Irp7k6mhVIG+rRY8sZprgvWtvqjx SRb70zB0XcVV8rwvWlkGWp1GsqCRjRi+LlSO+JNJhzk2qK43zl0DceiKNzB/HlXY26R3 anbSM1z8wI5Vji63tRUEQQVkC3ETZR6Az+zIoChZ1tqRsDkv8GSMxNcypJMYtf6sWv2o zXww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=wrcmbdNNJFx//dV10zYXdyJfZ8i9iBUOXuvlPxh7U7s=; b=aRCHXa3mMVobmqN910sIpGQJfmAkrnzE4ffrW+vSew+J0Z6ksCOp3X5B4FkX726h67 jXGJszM4FMTWqFYSvfoNxbD8wXrAX6oZp4sc8ikUT8x2B9ITrqqtlmdmgYqnNGeb30Z4 ss5tRpap2H4JS+pPp7bAilX9IRpfO6pdYhJkz1aoSwWj5t+ZU6yHT6VcHWnXH8Bwp/Sb OkH8V3bcuTZn+YtuivVZrfOuBfAkuUnkxZoaT4+Vl95PLEdx5mYsqSvYKit6lvL1fhFu V/XuWvL5SOtippGsUJmErK/IrtvJOsC13txZvT9ybPyYpDzXsYfAgmUV0jtM3c4BV7Dr H/hw== X-Gm-Message-State: AOAM531nygCzHLsY4DeLJY0c3bbPYjdq1Iv0yjZQ52n5NHtOznlHBedF RepjrBOQq2pRkSI/QEpncTeyJs4gahU= X-Google-Smtp-Source: ABdhPJyrgq1xOyo6KhCUAYnPbyS44d0I9RWp+8tMVgCjHXLWI6cTgW68efaiiawnOHF4PRt7HvD3ZEBPBDY= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:e033:4e8b:8f1:9bb4]) (user=glider job=sendgmr) by 2002:ad4:4810:: with SMTP id g16mr17927192qvy.21.1620976952308; Fri, 14 May 2021 00:22:32 -0700 (PDT) Date: Fri, 14 May 2021 09:22:28 +0200 Message-Id: <20210514072228.534418-1-glider@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.31.1.751.gd2f1c929bd-goog Subject: [PATCH] kasan: slab: always reset the tag in get_freepointer_safe() From: Alexander Potapenko To: akpm@linux-foundation.org Cc: Alexander Potapenko , Marco Elver , Vincenzo Frascino , Andrey Ryabinin , Andrey Konovalov , Elliot Berman , linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With CONFIG_DEBUG_PAGEALLOC enabled, the kernel should also untag the object pointer, as done in get_freepointer(). Failing to do so reportedly leads to SLUB freelist corruptions that manifest as boot-time crashes. Cc: Andrew Morton Cc: Marco Elver Cc: Vincenzo Frascino Cc: Andrey Ryabinin Cc: Andrey Konovalov Cc: Elliot Berman Cc: linux-kernel@vger.kernel.org Signed-off-by: Alexander Potapenko --- mm/slub.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/slub.c b/mm/slub.c index feda53ae62ba..9a4f59e5b0c2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -301,6 +301,7 @@ static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) if (!debug_pagealloc_enabled_static()) return get_freepointer(s, object); + object = kasan_reset_tag(object); freepointer_addr = (unsigned long)object + s->offset; copy_from_kernel_nofault(&p, (void **)freepointer_addr, sizeof(p)); return freelist_ptr(s, p, freepointer_addr); -- 2.31.1.751.gd2f1c929bd-goog