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=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 5B644C0650E for ; Wed, 3 Jul 2019 17:19:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EAC6E2184C for ; Wed, 3 Jul 2019 17:19:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="a7Rj0jY2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EAC6E2184C 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 61BB38E0009; Wed, 3 Jul 2019 13:19:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5CE4B8E0001; Wed, 3 Jul 2019 13:19:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4C32E8E0009; Wed, 3 Jul 2019 13:19:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-io1-f70.google.com (mail-io1-f70.google.com [209.85.166.70]) by kanga.kvack.org (Postfix) with ESMTP id 2BACD8E0001 for ; Wed, 3 Jul 2019 13:19:15 -0400 (EDT) Received: by mail-io1-f70.google.com with SMTP id n8so3264499ioo.21 for ; Wed, 03 Jul 2019 10:19:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:dkim-signature:mime-version:references :in-reply-to:from:date:message-id:subject:to:cc; bh=YGjByfD82DU0x9mX4FdRfeYlzBtivDKcJ0KQXu0Ie1I=; b=smUuvtQJ8Vp8kr1kxvVYhDhzD8zPmdUqWc1xfHkQclfgV6PQzVJ6WKa/khSyWRFGGs cC31Pc20hs5IJ/JTOJxdbYdoTRgJQ3n17HaJWLuP7WWHi2krlUjEPMIZ2RLl2O3mPLzi fa+zLvkSGIXFqs4FZgDBG/M9ef6QvZr8/YZ5Us92yd9mgO76aTVHwhoMq/v4sRdsXG9X lW2UZO9guVpHl/pZJVA05R3brrSXXUzBbXQ16d3MU6jhyO9JzTohxtH5nKEOi5xY1KX0 GLjWk5lbudAbL9J5zXb29pF1RDsisrl8HrljNDFDb87M5GZf+lihGNyX8SlwWjLEgrdI vuVw== X-Gm-Message-State: APjAAAVzO5Obg08OyRpGTyngX+mWG48UjMAuK3dNfFBkdWjqaMC9dwHi yxX7QKhoETGOzBqYzSAS80q08Akj/JqWsZuVs49bzpFPixUT15JlXcNFCHFu86NDEQJu9XKkVCv leUzkWD4wk+shjXPRUTjn3thM3pJiz/654xtq9TcGmFC1o5S1XTBoWnCVczPcPnv23A== X-Received: by 2002:a02:ab83:: with SMTP id t3mr43910380jan.133.1562174354861; Wed, 03 Jul 2019 10:19:14 -0700 (PDT) X-Received: by 2002:a02:ab83:: with SMTP id t3mr43910312jan.133.1562174354125; Wed, 03 Jul 2019 10:19:14 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1562174354; cv=none; d=google.com; s=arc-20160816; b=UJu0qWFm4znYD7HPL2ZCwdOAo6GtHlNEtQlqEoOGCI7+xT6BXC8zIE7UFLMJlMQnvA qgeREsBBhFu5C/Vorq8TyMZ7xXmFIfkyWYSdCYUlaI4QCVUeW0yFysT0u3tw+aT1OEu5 6jEKt9bHWpCh+K5bY/Qq+r1neIywdf5gOih7Oq2W2I7McKV5sawPCPLn1n8e3adBBTCW fBUlhV9FFXzOghIX+vl/47xVIPCA9ozptmENUnWfM6E63Z2Jl8i54P4mrf/owE7fo99Q BgHMBdt0khmqyNDijR5XmCzRy4Mgd6FGZGzimAfS5kUHZSV1xeRVD3Kk3p1d1a8nKVjV KcgQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:dkim-signature; bh=YGjByfD82DU0x9mX4FdRfeYlzBtivDKcJ0KQXu0Ie1I=; b=YNtIf/vURGFu13KNCwJl8Qlne6waqHKxbvfYapT7tFUTm7bkrC/hpnwznxlFnVexEV BPmYSvwkkOwitR0x1JSnsMlRLn+cR2SrPdIUJGyt0babOIrO5IyCLkKUA5xQyDX1uCfe uPhsFzyb7vgkTc5CD3kxarT8hmvTriLRW6bFKDWZrFabRk6I/PdAeKofqRwnQF9etvZn LkmHNa2LskgwgWKEby4fMh8/q4KRQlqas7dkKN0vWEwqapm/ufT615JxiOCGUuGTlQPf LhpQBd3UgD18VGxniNelk1nwsatYaxsYg2gErqZ+hrgvRTOqusgxH9/AG4w2ZfqoZXyn wJrw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=a7Rj0jY2; spf=pass (google.com: domain of henryburns@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=henryburns@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id j128sor2164721iof.121.2019.07.03.10.19.13 for (Google Transport Security); Wed, 03 Jul 2019 10:19:14 -0700 (PDT) Received-SPF: pass (google.com: domain of henryburns@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=a7Rj0jY2; spf=pass (google.com: domain of henryburns@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=henryburns@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com 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=YGjByfD82DU0x9mX4FdRfeYlzBtivDKcJ0KQXu0Ie1I=; b=a7Rj0jY2QBIfViPNFUm76trGe/bKUY7mCjPwJbiaJ50x6pJNRBkPu+R1MM8mw6sOOU 4B3aEJKjRb3+e7bU3IP1jFdb1YFmzDwlsN4MXd++Uf2Fp2Nzel29i8J9XQ22NojddDZB +Ulzkl67GjTVkp41624QkEl0E/s8o3qkxFuABwKgTE6kJYqMZA8jNskfHCbQOBk6pnzR NOpvtVVjeuJiet55kmS0P+X09nZ3dUpGlSld4TNhSinRaDzB2lEIW0iwUqau3LNF+c3h 39nW6JLRT+JrNz8eQ83heezlELAfEDy8iT1ms460iBM6Lt5wffeg7MZ2w0nk/P0WI2Ur Z3XQ== X-Google-Smtp-Source: APXvYqyUr71sdXpi43QYYZjncftgBxdzVnH8D2CCeSrP2TVbacVB/SQkZJ/WcE7USxtw+O12qqHaCQkIyrNp/Rpqopk= X-Received: by 2002:a5e:c207:: with SMTP id v7mr10360260iop.163.1562174353630; Wed, 03 Jul 2019 10:19:13 -0700 (PDT) MIME-Version: 1.0 References: <20190701173042.221453-1-henryburns@google.com> In-Reply-To: From: Henry Burns Date: Wed, 3 Jul 2019 10:18:37 -0700 Message-ID: Subject: Re: [PATCH] mm/z3fold: Fix z3fold_buddy_slots use after free To: Vitaly Wool Cc: Andrew Morton , Vitaly Vul , Mike Rapoport , Xidong Wang , Shakeel Butt , Jonathan Adams , Linux-MM , LKML Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000006, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > > On Tue, Jul 2, 2019 at 12:45 AM Vitaly Wool wrote: > > > > > > Hi Henry, > > > > > > On Mon, Jul 1, 2019 at 8:31 PM Henry Burns wrote: > > > > > > > > Running z3fold stress testing with address sanitization > > > > showed zhdr->slots was being used after it was freed. > > > > > > > > z3fold_free(z3fold_pool, handle) > > > > free_handle(handle) > > > > kmem_cache_free(pool->c_handle, zhdr->slots) > > > > release_z3fold_page_locked_list(kref) > > > > __release_z3fold_page(zhdr, true) > > > > zhdr_to_pool(zhdr) > > > > slots_to_pool(zhdr->slots) *BOOM* > > > > > > Thanks for looking into this. I'm not entirely sure I'm all for > > > splitting free_handle() but let me think about it. > > > > > > > Instead we split free_handle into two functions, release_handle() > > > > and free_slots(). We use release_handle() in place of free_handle(), > > > > and use free_slots() to call kmem_cache_free() after > > > > __release_z3fold_page() is done. > > > > > > A little less intrusive solution would be to move backlink to pool > > > from slots back to z3fold_header. Looks like it was a bad idea from > > > the start. > > > > > > Best regards, > > > Vitaly > > > > We still want z3fold pages to be movable though. Wouldn't moving > > the backink to the pool from slots to z3fold_header prevent us from > > enabling migration? > > That is a valid point but we can just add back pool pointer to > z3fold_header. The thing here is, there's another patch in the > pipeline that allows for a better (inter-page) compaction and it will > somewhat complicate things, because sometimes slots will have to be > released after z3fold page is released (because they will hold a > handle to another z3fold page). I would prefer that we just added back > pool to z3fold_header and changed zhdr_to_pool to just return > zhdr->pool, then had the compaction patch valid again, and then we > could come back to size optimization. I see your point, patch incoming.