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=-10.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 26230C433E6 for ; Mon, 20 Jul 2020 15:48:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 018AB22CAF for ; Mon, 20 Jul 2020 15:48:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260107; bh=xYNtf1K9Clxoc111B6sXE1QVfCLFVpgTKazDwptjWFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hfITBd0Z2jXsCxdKV2rWKjc4JFWlR+ZqMExdI5yNkHzc9Hkb/6tIpAwIyVNpQDP7S NoxJ3pqmPyV1+090uUUybDTQ9wgWQk7q7HzT769268mTtMzzcqm8BsGOcKcIGKo3xN IkGjWWNbIIoCZ/H82qmL1FhB8SH6NPAUfOY4BA5U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729417AbgGTPsZ (ORCPT ); Mon, 20 Jul 2020 11:48:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:43982 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730145AbgGTPsX (ORCPT ); Mon, 20 Jul 2020 11:48:23 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 031EA22CAF; Mon, 20 Jul 2020 15:48:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260102; bh=xYNtf1K9Clxoc111B6sXE1QVfCLFVpgTKazDwptjWFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wKNqzX02VAQYAs1JGzbGZvScfDJqm7I9ot8+zVEsuOw4DhY4XR9b5vQjere6P8/MO G5OHrYnPMkEbzRTs125E8MTL99HzE8oFTAfMMVuItu7/cLmX5pl4htwG/Hdtf1aeO/ UFfKUQJRQoArOTGhnM4dxiKEOvOa/ndjFdzFNOFc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chirantan Ekbote , Miklos Szeredi Subject: [PATCH 4.14 107/125] fuse: Fix parameter for FS_IOC_{GET,SET}FLAGS Date: Mon, 20 Jul 2020 17:37:26 +0200 Message-Id: <20200720152808.195336396@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152802.929969555@linuxfoundation.org> References: <20200720152802.929969555@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chirantan Ekbote commit 31070f6ccec09f3bd4f1e28cd1e592fa4f3ba0b6 upstream. The ioctl encoding for this parameter is a long but the documentation says it should be an int and the kernel drivers expect it to be an int. If the fuse driver treats this as a long it might end up scribbling over the stack of a userspace process that only allocated enough space for an int. This was previously discussed in [1] and a patch for fuse was proposed in [2]. From what I can tell the patch in [2] was nacked in favor of adding new, "fixed" ioctls and using those from userspace. However there is still no "fixed" version of these ioctls and the fact is that it's sometimes infeasible to change all userspace to use the new one. Handling the ioctls specially in the fuse driver seems like the most pragmatic way for fuse servers to support them without causing crashes in userspace applications that call them. [1]: https://lore.kernel.org/linux-fsdevel/20131126200559.GH20559@hall.aurel32.net/T/ [2]: https://sourceforge.net/p/fuse/mailman/message/31771759/ Signed-off-by: Chirantan Ekbote Fixes: 59efec7b9039 ("fuse: implement ioctl support") Cc: Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/fuse/file.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -17,6 +17,7 @@ #include #include #include +#include static const struct file_operations fuse_direct_io_file_operations; @@ -2534,7 +2535,16 @@ long fuse_do_ioctl(struct file *file, un struct iovec *iov = iov_page; iov->iov_base = (void __user *)arg; - iov->iov_len = _IOC_SIZE(cmd); + + switch (cmd) { + case FS_IOC_GETFLAGS: + case FS_IOC_SETFLAGS: + iov->iov_len = sizeof(int); + break; + default: + iov->iov_len = _IOC_SIZE(cmd); + break; + } if (_IOC_DIR(cmd) & _IOC_WRITE) { in_iov = iov;