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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B9D1C433EF for ; Tue, 15 Feb 2022 20:47:10 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2553F6B0078; Tue, 15 Feb 2022 15:47:10 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2052D6B007B; Tue, 15 Feb 2022 15:47:10 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0A68B6B007D; Tue, 15 Feb 2022 15:47:10 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0028.hostedemail.com [216.40.44.28]) by kanga.kvack.org (Postfix) with ESMTP id F17956B0078 for ; Tue, 15 Feb 2022 15:47:09 -0500 (EST) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 9D6F4951A9 for ; Tue, 15 Feb 2022 20:47:09 +0000 (UTC) X-FDA: 79146198978.08.B2F5287 Received: from mail-yb1-f169.google.com (mail-yb1-f169.google.com [209.85.219.169]) by imf31.hostedemail.com (Postfix) with ESMTP id 3EACA20006 for ; Tue, 15 Feb 2022 20:47:09 +0000 (UTC) Received: by mail-yb1-f169.google.com with SMTP id l125so26800938ybl.4 for ; Tue, 15 Feb 2022 12:47:08 -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=S8Me6KM4X/g4+r5dBOOOSbnzBOmx1bs5mOtlD8G04HGjRZ0zPqaKo6Waet6++rOcV8 Un0AjoFrr0yuB7XGs2yzNYg2MQL/Rk5Yg2B/5I/8NFQyXeb1oNIjm1ZEg8VFJ6Mlh5L+ 89VPRICQ5s4qvvZGJtFS3xK9ViI0J1EVhhQMWzmKHsA6HyAKdTJoNp7WZs42VVo7uy6i 5QNrg3UwHycNdm48Qri6Jk1yMuL/g3EiWUagnwKobmeL1ctfa/zcg71x89I9MeYgs+wK Oo98r22bdMT/JWJu8XoahK861NrMNHtnEQetfe6Ac6vxnKk3OtE0Vzj19HdGkVRcMPp8 7KGA== X-Gm-Message-State: AOAM533gnKhtmMh7UROkwpWhBXzL5W8S9BwXLRdOnPfn0BplOGYEvzDx aXiiU8uHAdPZeB4STVqzz3cbv4kVA5iwH7bgBYNjnA== 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" Authentication-Results: imf31.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=fr6oWxoT; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf31.hostedemail.com: domain of surenb@google.com designates 209.85.219.169 as permitted sender) smtp.mailfrom=surenb@google.com X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 3EACA20006 X-Stat-Signature: b4ymzgpbhtgn3wzt1x1tmmmu5aaijfe3 X-HE-Tag: 1644958029-122910 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 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.