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 A0520C4741F for ; Fri, 30 Oct 2020 15:42:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0AA072087E for ; Fri, 30 Oct 2020 15:42:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DTRV++Wj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0AA072087E 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 C428E6B0070; Fri, 30 Oct 2020 11:42:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BF1366B0071; Fri, 30 Oct 2020 11:42:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ABA0E6B0073; Fri, 30 Oct 2020 11:42:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0125.hostedemail.com [216.40.44.125]) by kanga.kvack.org (Postfix) with ESMTP id 6F1FE6B0070 for ; Fri, 30 Oct 2020 11:42:10 -0400 (EDT) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 0702F181AEF10 for ; Fri, 30 Oct 2020 15:42:10 +0000 (UTC) X-FDA: 77429008020.17.chain24_380241727297 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id C18F4180D0181 for ; Fri, 30 Oct 2020 15:42:09 +0000 (UTC) X-HE-Tag: chain24_380241727297 X-Filterd-Recvd-Size: 5334 Received: from mail-oi1-f196.google.com (mail-oi1-f196.google.com [209.85.167.196]) by imf05.hostedemail.com (Postfix) with ESMTP for ; Fri, 30 Oct 2020 15:42:09 +0000 (UTC) Received: by mail-oi1-f196.google.com with SMTP id l62so1406575oig.1 for ; Fri, 30 Oct 2020 08:42:09 -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=jliMwvFbMuf3FmeyCOZHebsGYCHgE565UHogT5/5F4c=; b=DTRV++Wj97wRkgJERXq0rJLt5u61M6aqsGpPrrOnjKGZx0REQwXzkR/pMuc8yZvrEZ g2R1TVm26ePxCZVC0YEei38ODl21B1c3cWcMr2+PJorWGXwMP6J5U0Ntm+10TM2p6tJV CpCTQDAOD8oVls4YRHUrINL85+YtP9RuBxOGPHozp/ye9UomJjfrAgkI4rC1viw6jBG1 u1uT9ybUrxa3TuQUNEFsK7bR9VjHCl2kWaOmTzJSlRJDGUptBLq263qR0rJJEHAyP3Aj vpPFDPfu3rWEXImVRC/Ipfyq5ldHGwmYoQ/ppzDNpXCJDsezNiAo0JKRBtZ5i7/I6ZB9 zmgQ== 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=jliMwvFbMuf3FmeyCOZHebsGYCHgE565UHogT5/5F4c=; b=W1rn6wi4ixniNYh4E/faMIYp6c3zHNuvok+/pKKtEzf4+RH2Rek4MzBDL4wJcqpivR o/fLH1Li7+SZVJ5rNmaYNS4JY3iFq4bX6fhrzDzzpm3JuWj1bOlKifXy9nQ3JNVGmIrR 7gt8aQ5pt2dSFoB//VFb1y1XgtRJlyKw3/bWo8lexH6eRs4iuaxPHXQK64Ymt/0ZqgUC AwLNGFbh2f9Da8ymzNZncmh6fsVfh4JWVrnRcQu5F7UJLXH6Goco/z01rqikb8VxegKu GBHqAl49tL11PZ2AWhEAN8D/ogF+PPwGkqE1BGD51CPGBx++zzuuyXGpKZmFgOu2yjHU GqBw== X-Gm-Message-State: AOAM532WkOOcwFW4z232AImzfS/tTXfe1Mh4zxdfpTA7FAQJ5co+9ePv sS8h/laM2Bc/JSL8fEj3cWBq55PafDiZueZ6c1WEHQ== X-Google-Smtp-Source: ABdhPJz78rXAmUYJT2EaihG4wO2tbRCMfvht01XOnXsfIeEuKEo7TR1erogbgNJurtY7525vFsiGR0VO98zOblDC/OA= X-Received: by 2002:aca:6206:: with SMTP id w6mr2138653oib.121.1604072528251; Fri, 30 Oct 2020 08:42:08 -0700 (PDT) MIME-Version: 1.0 References: <20201029131649.182037-1-elver@google.com> <20201029131649.182037-5-elver@google.com> In-Reply-To: From: Marco Elver Date: Fri, 30 Oct 2020 16:41:56 +0100 Message-ID: Subject: Re: [PATCH v6 4/9] mm, kfence: insert KFENCE hooks for SLAB To: Jann Horn 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 , =?UTF-8?Q?J=C3=B6rn_Engel?= , 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 Fri, 30 Oct 2020 at 03:49, Jann Horn wrote: > 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); Good catch. Although extremely unlikely, let's just avoid it by moving the freeing after. > > > + > > /* Put the object into the quarantine, don't touch it for now. */ > > if (kasan_slab_free(cachep, objp, _RET_IP_)) > > return;