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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8BCD0C433F5 for ; Tue, 15 Feb 2022 20:47:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244160AbiBOUrX (ORCPT ); Tue, 15 Feb 2022 15:47:23 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:34466 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244152AbiBOUrU (ORCPT ); Tue, 15 Feb 2022 15:47:20 -0500 Received: from mail-yb1-xb2d.google.com (mail-yb1-xb2d.google.com [IPv6:2607:f8b0:4864:20::b2d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A58B1106 for ; Tue, 15 Feb 2022 12:47:09 -0800 (PST) Received: by mail-yb1-xb2d.google.com with SMTP id v63so32749104ybv.10 for ; Tue, 15 Feb 2022 12:47:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=T41ePHFV0yFOOsXNClLAtA/x+o8KEy6AoDggp2srYzE=; b=fr6oWxoTzDtbYvaxIXq0fUxpvVr0x04DUX5wLQBL8LKzXgQVWGbjoar2jjdjM5S1DV 1urfngwM9WhtMp3MY6OKMFOt6Jo2o0gZx6M32xFP8vkPMdtbyN9ggBMfIarNp+JgPFUg qWOq0wn8fOMEv15+6TItR2l2a83yNtoGiWl5M8ceFQsEB9Rlearzj25BbwVcYKEZHQAh +m/MIN5TkqRXbquBnmVjQot2oXFVaFCpQjQWFYIZffzxrPF+N/DKFyiIRLnHadLWes7Y zxm+yrUYvmVyrzBotDtotfADyjAF43d2qPAYPrliG1q/RQOf+PQOJ/nmxg3lTPexDb5e voAg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=T41ePHFV0yFOOsXNClLAtA/x+o8KEy6AoDggp2srYzE=; b=QHF7BBOBOufG4/IoO1fisl8Jr0i0PUE4DLEYIpWx2q7gDfURvhNZAhXUpsFGzQSE1w cxbJkYoWvnvBG61mzpgkGl6m8hUkmoVUNZmkeOM46HSAz+StAFxc/8NOdMbxgVqm0IQK B3p7KohRybM/n4LuD0WoAwT91H9Zq1qc97TOIUTwA9LMOWMV/JJkfl4dW2i4O7ou6jxg aTkOtEX+sKYZVDpkyV6p6jdE2Z5BiCHDDx4aDJT3hDV24KXIpRbkkxWEVk6axZDmC5Tp Kv77RHbxhP2bBUH0X3t1v/diYmmJsc5fDZ2CBghCYZBq2dXbrzK97ivPaqN3tsS/7bik GBoQ== X-Gm-Message-State: AOAM532Pg5af7ToMzYe7CwD7/dF3xRvn5vPIoGI3SW9CmmavRB3M1ifS ip0z8wk4aFbLgz1ihYOvfWzQUvYuRlpP3bf8vlxBlA== X-Google-Smtp-Source: ABdhPJwmdsuGjYfrOBPnDQhg/eRtU1Bu9W51ZB3QJAQWKMXfxyjW5ctW4UNISdKp6Akvl97iJFnpc7j/a/gdYJyxd2U= X-Received: by 2002:a25:d212:: with SMTP id j18mr720145ybg.243.1644958028195; Tue, 15 Feb 2022 12:47:08 -0800 (PST) MIME-Version: 1.0 References: <20220215201922.1908156-1-surenb@google.com> <20220215123741.8e757b337e1f2d32a1766d42@linux-foundation.org> In-Reply-To: From: Suren Baghdasaryan Date: Tue, 15 Feb 2022 12:46:57 -0800 Message-ID: Subject: Re: [PATCH 1/1] mm: fix use-after-free bug when mm->mmap is reused after being freed To: Andrew Morton Cc: Michal Hocko , Michal Hocko , Yang Shi , David Rientjes , Matthew Wilcox , Johannes Weiner , Roman Gushchin , Rik van Riel , Minchan Kim , "Kirill A. Shutemov" , Andrea Arcangeli , Christian Brauner , Christian Brauner , Christoph Hellwig , Oleg Nesterov , David Hildenbrand , Jann Horn , Shakeel Butt , Andy Lutomirski , Christian Brauner , Florian Weimer , Jan Engelhardt , Tim Murray , linux-mm , LKML , kernel-team , syzbot Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 15, 2022 at 12:45 PM Suren Baghdasaryan wrote: > > On Tue, Feb 15, 2022 at 12:37 PM Andrew Morton > wrote: > > > > On Tue, 15 Feb 2022 12:19:22 -0800 Suren Baghdasaryan wrote: > > > > > After exit_mmap frees all vmas in the mm, mm->mmap needs to be reset, > > > otherwise it points to a vma that was freed and when reused leads to > > > a use-after-free bug. > > > > > > ... > > > > > > --- a/mm/mmap.c > > > +++ b/mm/mmap.c > > > @@ -3186,6 +3186,7 @@ void exit_mmap(struct mm_struct *mm) > > > vma = remove_vma(vma); > > > cond_resched(); > > > } > > > + mm->mmap = NULL; > > > mmap_write_unlock(mm); > > > vm_unacct_memory(nr_accounted); > > > } > > > > https://lore.kernel.org/all/00000000000072ef2c05d7f81950@google.com/ > > > > It would be nice to have a Fixes: for this. > > Oh, right. Should be: > > Fixes: 64591e8605d6 ("mm: protect free_pgtables with mmap_lock write > lock in exit_mmap") Andrew, do you want me to post another version with Fixes: 64591e8605d6 ("mm: protect free_pgtables with mmap_lock write lock in exit_mmap") added or you can add it directly? > > > > > Is it specific to process_mrelease(), or should we backport further? > > The broken change is recent and was introduced in v5.17-rc1.