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=-14.4 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 4BBF3C4363A for ; Fri, 30 Oct 2020 02:50:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 98CF62087D for ; Fri, 30 Oct 2020 02:50:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="etxHYnTq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 98CF62087D Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 252126B007B; Thu, 29 Oct 2020 22:50:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1DE836B007D; Thu, 29 Oct 2020 22:50:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 07D116B007E; Thu, 29 Oct 2020 22:50:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0103.hostedemail.com [216.40.44.103]) by kanga.kvack.org (Postfix) with ESMTP id CCA7E6B007B for ; Thu, 29 Oct 2020 22:50:00 -0400 (EDT) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 6D4651EE6 for ; Fri, 30 Oct 2020 02:50:00 +0000 (UTC) X-FDA: 77427062160.04.hat94_580333e27292 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id 52995800CBD7 for ; Fri, 30 Oct 2020 02:50:00 +0000 (UTC) X-HE-Tag: hat94_580333e27292 X-Filterd-Recvd-Size: 4994 Received: from mail-lj1-f194.google.com (mail-lj1-f194.google.com [209.85.208.194]) by imf28.hostedemail.com (Postfix) with ESMTP for ; Fri, 30 Oct 2020 02:49:59 +0000 (UTC) Received: by mail-lj1-f194.google.com with SMTP id 2so5295522ljj.13 for ; Thu, 29 Oct 2020 19:49:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Z9WOxdh6RCpZm8X6kMwbW3XPGG0WSUUUAze88LfZLdE=; b=etxHYnTqjwBUbwtfAT9j7VihFyCPL/m5eoH6lV63Jwf/ogaS8IKuC/qJ0F2t2aJCTu YcXfkY8v4/Ze8lP8pZWLnoMm5+afhhjmu2kX8tx4XUTc2g3+taqkP5iw5O/XxbrXeokh /Z4gZPHmELyAamNnAVQZEPpF1z6I7AvobWo9rXIWQ4W9PVyMLUg7pHsdscCI4vcHhut2 KDKv2h0XeSjZIlzeLYggI3qsLbeEI5HKczEYovWFfTlfU5RcMT5lRZ2+Xe9rQ1O/YFlY Bjdk2siK5slwbxSG7EkMj23241i3jE2SX9x0CZ83wo0uv4SrDXzDA4uTA7PNluOo5tQY TYeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Z9WOxdh6RCpZm8X6kMwbW3XPGG0WSUUUAze88LfZLdE=; b=O3+EiQFaoRB4Vtb7FDiVlJ9klrwcTo4g5E213IE4wxXfwWPYW8mojIL1V475YxJqXU OVMzGlmEqz6PWVSD6fLEG+Vk9gCNeu1+dTHUfnYJ4WIzdiV5mYlEnMR31W9tbEaI/Icx E5i9dI53gWV9mLH43t002dWUjTib1+pGu9oTX+qQSHKhua4xYM7i2MuZz51nmbucvTP/ p9bPWHZiaqDccUqw22Z6fZBZsIgWixuXgTw2jaiNiFIytw9U6PtOypRzmEV9WJpJ4J7y 4qmPDklFu9cCxqh4BeV4wso080ivOFH+7t1P5ytykoI9k03YuBl0UNteyPocGkU7Fu6X 8+Ng== X-Gm-Message-State: AOAM530m4moNR0rwRgFrpluMjLfsptTujwYiKFxu7Tp2y7KFfFIj1keo FTIPJXBmfv4wPJqx64XFp55oAnIQPMsXnEAWzXy6lQ== X-Google-Smtp-Source: ABdhPJwE/Q8Xn7eqLDDiYpTHlTjaaBJjfas81RL+GS05oC24gJGCW+LBgod9ZKVq7Rn7XWiNj/59sO4G5qgTD6gJ5JY= X-Received: by 2002:a05:651c:1313:: with SMTP id u19mr95728lja.47.1604026198405; Thu, 29 Oct 2020 19:49:58 -0700 (PDT) MIME-Version: 1.0 References: <20201029131649.182037-1-elver@google.com> <20201029131649.182037-5-elver@google.com> In-Reply-To: <20201029131649.182037-5-elver@google.com> From: Jann Horn Date: Fri, 30 Oct 2020 03:49:31 +0100 Message-ID: Subject: Re: [PATCH v6 4/9] mm, kfence: insert KFENCE hooks for SLAB To: Marco Elver Cc: Andrew Morton , Alexander Potapenko , "H . Peter Anvin" , "Paul E . McKenney" , Andrey Konovalov , Andrey Ryabinin , Andy Lutomirski , Borislav Petkov , Catalin Marinas , Christoph Lameter , Dave Hansen , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Hillf Danton , Ingo Molnar , Jonathan Cameron , Jonathan Corbet , Joonsoo Kim , joern@purestorage.com, Kees Cook , Mark Rutland , Pekka Enberg , Peter Zijlstra , SeongJae Park , Thomas Gleixner , Vlastimil Babka , Will Deacon , "the arch/x86 maintainers" , "open list:DOCUMENTATION" , kernel list , kasan-dev , Linux ARM , Linux-MM Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Oct 29, 2020 at 2:17 PM Marco Elver wrote: > Inserts KFENCE hooks into the SLAB allocator. [...] > diff --git a/mm/slab.c b/mm/slab.c [...] > @@ -3416,6 +3427,11 @@ static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac) > static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp, > unsigned long caller) > { > + if (kfence_free(objp)) { > + kmemleak_free_recursive(objp, cachep->flags); > + return; > + } This looks dodgy. Normally kmemleak is told that an object is being freed *before* the object is actually released. I think that if this races really badly, we'll make kmemleak stumble over this bit in create_object(): kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n", ptr); > + > /* Put the object into the quarantine, don't touch it for now. */ > if (kasan_slab_free(cachep, objp, _RET_IP_)) > return;