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=-7.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9E9F7C433E0 for ; Tue, 4 Aug 2020 20:45:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72ED021744 for ; Tue, 4 Aug 2020 20:45:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596573947; bh=IsGGbZDqwVSdrx08mN8MiNfmLHPAXTc8CpjLyRYm0PY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=ccZqN0hFe8J4ELmURv9ZM3wz8oYHCxX7FZ6vVqXScL+zWhZINoMpbH+Haf5wxu6tk N1XqA7/E5sL5nao0BidEEonPdTOCneNu9UMZrO8jkV9Fn9z0VdQ6FCjgnarwIc8PUF pRIXc/35gYZBNwbHB9bTWNIfiYS6c8cyIvd1wm30= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727849AbgHDUpq (ORCPT ); Tue, 4 Aug 2020 16:45:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:36342 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726545AbgHDUpp (ORCPT ); Tue, 4 Aug 2020 16:45:45 -0400 Received: from gmail.com (unknown [104.132.1.76]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 10B7920842; Tue, 4 Aug 2020 20:45:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596573945; bh=IsGGbZDqwVSdrx08mN8MiNfmLHPAXTc8CpjLyRYm0PY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=k2RYgdBKRUZvYgyXaVkxI8tIV9M60Ul5vpeFSWkbA6mYNzNXbdFZe+/fRj/AcZNdn Oc+boojGMwh1YfBWUsY2MnjY9quPxdG9/jl7c7lhkNXKUyVtVMayworct1WUEyMmVK vXEszlOdY79qUbEtjI3wfBf7j1/A5vn32NCZKPBY= Date: Tue, 4 Aug 2020 13:45:43 -0700 From: Eric Biggers To: Lokesh Gidra Cc: viro@zeniv.linux.org.uk, stephen.smalley.work@gmail.com, casey@schaufler-ca.com, jmorris@namei.org, kaleshsingh@google.com, dancol@dancol.org, surenb@google.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, nnk@google.com, jeffv@google.com, calin@google.com, kernel-team@android.com, yanfei.xu@windriver.com, syzbot+75867c44841cb6373570@syzkaller.appspotmail.com Subject: Re: [PATCH] Userfaultfd: Avoid double free of userfault_ctx and remove O_CLOEXEC Message-ID: <20200804204543.GA1992048@gmail.com> References: <20200804203155.2181099-1-lokeshgidra@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200804203155.2181099-1-lokeshgidra@google.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 04, 2020 at 01:31:55PM -0700, Lokesh Gidra wrote: > when get_unused_fd_flags returns error, ctx will be freed by > userfaultfd's release function, which is indirectly called by fput(). > Also, if anon_inode_getfile_secure() returns an error, then > userfaultfd_ctx_put() is called, which calls mmdrop() and frees ctx. > > Also, the O_CLOEXEC was inadvertently added to the call to > get_unused_fd_flags() [1]. > > Adding Al Viro's suggested-by, based on [2]. > > [1] https://lore.kernel.org/lkml/1f69c0ab-5791-974f-8bc0-3997ab1d61ea@dancol.org/ > [2] https://lore.kernel.org/lkml/20200719165746.GJ2786714@ZenIV.linux.org.uk/ > > Fixes: d08ac70b1e0d (Wire UFFD up to SELinux) > Suggested-by: Al Viro > Reported-by: syzbot+75867c44841cb6373570@syzkaller.appspotmail.com > Signed-off-by: Lokesh Gidra What branch does this patch apply to? Neither mainline nor linux-next works. - Eric