From patchwork Thu Apr 14 13:08:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 561923 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 86810C433EF for ; Thu, 14 Apr 2022 13:14:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243741AbiDNNRV (ORCPT ); Thu, 14 Apr 2022 09:17:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243739AbiDNNRR (ORCPT ); Thu, 14 Apr 2022 09:17:17 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0FD1419018; Thu, 14 Apr 2022 06:14:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A3BAC610A6; Thu, 14 Apr 2022 13:14:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B4D1CC385A5; Thu, 14 Apr 2022 13:14:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649942091; bh=fnj2UimYQMMjPRsE2zFLIwHLfXhVxpRHD7otGr/6Ilw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b1Y2BvJCzjttLh6CJljC8uyqoComv7CSVmgvuhyw/2br+fyoqUAgdKAuwSlOF857D M3wRLSnkaQwP8VmGknDLmkmAmIh7kwUtG/r5DBoSkraZASTNBs4nbymzcf5FY/giMb xgba5uOpQyymAIaQQs/p0O7yUquLsFGIA3MuCWS8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , Miklos Szeredi , Zach OKeefe Subject: [PATCH 4.19 012/338] fuse: fix pipe buffer lifetime for direct_io Date: Thu, 14 Apr 2022 15:08:35 +0200 Message-Id: <20220414110839.241541230@linuxfoundation.org> X-Mailer: git-send-email 2.35.2 In-Reply-To: <20220414110838.883074566@linuxfoundation.org> References: <20220414110838.883074566@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Miklos Szeredi commit 0c4bcfdecb1ac0967619ee7ff44871d93c08c909 upstream. In FOPEN_DIRECT_IO mode, fuse_file_write_iter() calls fuse_direct_write_iter(), which normally calls fuse_direct_io(), which then imports the write buffer with fuse_get_user_pages(), which uses iov_iter_get_pages() to grab references to userspace pages instead of actually copying memory. On the filesystem device side, these pages can then either be read to userspace (via fuse_dev_read()), or splice()d over into a pipe using fuse_dev_splice_read() as pipe buffers with &nosteal_pipe_buf_ops. This is wrong because after fuse_dev_do_read() unlocks the FUSE request, the userspace filesystem can mark the request as completed, causing write() to return. At that point, the userspace filesystem should no longer have access to the pipe buffer. Fix by copying pages coming from the user address space to new pipe buffers. Reported-by: Jann Horn Fixes: c3021629a0d8 ("fuse: support splice() reading from fuse device") Cc: Signed-off-by: Miklos Szeredi Signed-off-by: Zach O'Keefe Signed-off-by: Greg Kroah-Hartman --- fs/fuse/dev.c | 12 +++++++++++- fs/fuse/file.c | 1 + fs/fuse/fuse_i.h | 2 ++ 3 files changed, 14 insertions(+), 1 deletion(-) --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -999,7 +999,17 @@ static int fuse_copy_page(struct fuse_co while (count) { if (cs->write && cs->pipebufs && page) { - return fuse_ref_page(cs, page, offset, count); + /* + * Can't control lifetime of pipe buffers, so always + * copy user pages. + */ + if (cs->req->user_pages) { + err = fuse_copy_fill(cs); + if (err) + return err; + } else { + return fuse_ref_page(cs, page, offset, count); + } } else if (!cs->len) { if (cs->move_pages && page && offset == 0 && count == PAGE_SIZE) { --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -1329,6 +1329,7 @@ static int fuse_get_user_pages(struct fu (PAGE_SIZE - ret) & (PAGE_SIZE - 1); } + req->user_pages = true; if (write) req->in.argpages = 1; else --- a/fs/fuse/fuse_i.h +++ b/fs/fuse/fuse_i.h @@ -313,6 +313,8 @@ struct fuse_req { /** refcount */ refcount_t count; + bool user_pages; + /** Unique ID for the interrupt request */ u64 intr_unique;