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=-7.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 E3750C43441 for ; Mon, 26 Nov 2018 11:01:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9690A21479 for ; Mon, 26 Nov 2018 11:01:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hGPLPQDH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9690A21479 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730090AbeKZVzB (ORCPT ); Mon, 26 Nov 2018 16:55:01 -0500 Received: from mail.kernel.org ([198.145.29.99]:37378 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728901AbeKZVzB (ORCPT ); Mon, 26 Nov 2018 16:55:01 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 96D662146F; Mon, 26 Nov 2018 11:01:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543230076; bh=ekPJGC4CBt+K2TuFOd4QXSubVxQxwG3tr7apE/giuLg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hGPLPQDHilirQ1QSjXlvZKQIQeOcxl4hkSpHSf4LjWrs+yVNgm6g4T0MknHaErGG/ 0cTgFEDoL8P7tdhYMkyVxcGh/IrQPq7SmdiFmZnHvQhIoJ8fo+iTmojBUHi8S8D+8d 9EJgmVs47APBKkdBSAoM1VeG7xnRHg4K8S5eqPMU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+72473edc9bf4eb1c6556@syzkaller.appspotmail.com, Jann Horn , Andy Lutomirski , Eric Biggers , Jiri Kosina Subject: [PATCH 4.14 61/62] HID: uhid: forbid UHID_CREATE under KERNEL_DS or elevated privileges Date: Mon, 26 Nov 2018 11:51:42 +0100 Message-Id: <20181126105055.130476030@linuxfoundation.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181126105050.592727680@linuxfoundation.org> References: <20181126105050.592727680@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review 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 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Biggers commit 8c01db7619f07c85c5cd81ec5eb83608b56c88f5 upstream. When a UHID_CREATE command is written to the uhid char device, a copy_from_user() is done from a user pointer embedded in the command. When the address limit is KERNEL_DS, e.g. as is the case during sys_sendfile(), this can read from kernel memory. Alternatively, information can be leaked from a setuid binary that is tricked to write to the file descriptor. Therefore, forbid UHID_CREATE in these cases. No other commands in uhid_char_write() are affected by this bug and UHID_CREATE is marked as "obsolete", so apply the restriction to UHID_CREATE only rather than to uhid_char_write() entirely. Thanks to Dmitry Vyukov for adding uhid definitions to syzkaller and to Jann Horn for commit 9da3f2b740544 ("x86/fault: BUG() when uaccess helpers fault on kernel addresses"), allowing this bug to be found. Reported-by: syzbot+72473edc9bf4eb1c6556@syzkaller.appspotmail.com Fixes: d365c6cfd337 ("HID: uhid: add UHID_CREATE and UHID_DESTROY events") Cc: # v3.6+ Cc: Jann Horn Cc: Andy Lutomirski Signed-off-by: Eric Biggers Reviewed-by: Jann Horn Signed-off-by: Jiri Kosina Signed-off-by: Greg Kroah-Hartman --- drivers/hid/uhid.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) --- a/drivers/hid/uhid.c +++ b/drivers/hid/uhid.c @@ -12,6 +12,7 @@ #include #include +#include #include #include #include @@ -722,6 +723,17 @@ static ssize_t uhid_char_write(struct fi switch (uhid->input_buf.type) { case UHID_CREATE: + /* + * 'struct uhid_create_req' contains a __user pointer which is + * copied from, so it's unsafe to allow this with elevated + * privileges (e.g. from a setuid binary) or via kernel_write(). + */ + if (file->f_cred != current_cred() || uaccess_kernel()) { + pr_err_once("UHID_CREATE from different security context by process %d (%s), this is not allowed.\n", + task_tgid_vnr(current), current->comm); + ret = -EACCES; + goto unlock; + } ret = uhid_dev_create(uhid, &uhid->input_buf); break; case UHID_CREATE2: