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 4C9E5C433F1 for ; Mon, 20 Jul 2020 15:55:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22D632065E for ; Mon, 20 Jul 2020 15:55:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260539; bh=9IYFXvNdzrOsWw+bw1eHWtHAmTn0VG0xwVdxYbgrFo4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=D80+wRQEfGOEv2C5bo6JWJBqFm3VSote61J5TFFJ9zaGBXOUJu7AdkwGM5G3eDj0p 1qLkuVDR4Klpp+/U8DnhSxd8iBV0W9ugLHfc3lwYdkVeblhqQznQKiBS4RU06JiWJr 92A6dVGa1Q89GADgA30K2YOtwI0JMJjtkpG40198= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731057AbgGTPzh (ORCPT ); Mon, 20 Jul 2020 11:55:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:54668 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731008AbgGTPzd (ORCPT ); Mon, 20 Jul 2020 11:55:33 -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 3D21C2065E; Mon, 20 Jul 2020 15:55:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595260532; bh=9IYFXvNdzrOsWw+bw1eHWtHAmTn0VG0xwVdxYbgrFo4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=V6VmSkhb2YZlqtvZ+iHtLB2eYvG0KFV2eXNIqx9HGBH5r884e+hDweS0Kb6XZdNUF INbly9oEc5bALn5wtitkJxsCpcqkuha6QQ6nMYFQZ+0agB2FoqA4CykxTWzj80CDHA mRezr+OLExRaH786hvKE9ZXfqCN/FeyfXlg3ZUJc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chirantan Ekbote , Miklos Szeredi Subject: [PATCH 4.19 106/133] fuse: Fix parameter for FS_IOC_{GET,SET}FLAGS Date: Mon, 20 Jul 2020 17:37:33 +0200 Message-Id: <20200720152808.866418357@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200720152803.732195882@linuxfoundation.org> References: <20200720152803.732195882@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 @@ -18,6 +18,7 @@ #include #include #include +#include static const struct file_operations fuse_direct_io_file_operations; @@ -2535,7 +2536,16 @@ 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;