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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by aws-us-west-2-korg-lkml-1.web.codeaurora.org (Postfix) with ESMTP id 7B3AAC433EF for ; Wed, 13 Jun 2018 01:47:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3921020660 for ; Wed, 13 Jun 2018 01:47:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3921020660 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=owl.eu.com 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 S934364AbeFMBrv (ORCPT ); Tue, 12 Jun 2018 21:47:51 -0400 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:53973 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932985AbeFMBrv (ORCPT ); Tue, 12 Jun 2018 21:47:51 -0400 X-Originating-IP: 70.80.172.8 Received: from localhost (modemcable008.172-80-70.mc.videotron.ca [70.80.172.8]) (Authenticated sender: hle@owl.eu.com) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id BDDB460014; Wed, 13 Jun 2018 01:47:45 +0000 (UTC) Date: Tue, 12 Jun 2018 21:47:41 -0400 From: Hugo Lefeuvre To: Greg Kroah-Hartman Cc: devel@driverdev.osuosl.org, linux-kernel@vger.kernel.org, kernelnewbies@kernelnewbies.org, Dan Carpenter , Marcus Wolf Subject: [PATCH v2] staging: pi433: fix race condition in pi433_ioctl Message-ID: <20180613014741.GC2265@hle-laptop.local> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In the PI433_IOC_WR_TX_CFG case in pi433_ioctl, instance->tx_cfg is modified via copy_from_user(&instance->tx_cfg, argp, sizeof(struct pi433_tx_cfg))) without any kind of synchronization. In the case where two threads would execute this same command concurrently the tx_cfg field might enter in an inconsistent state. Additionally: if ioctl(PI433_IOC_WR_TX_CFG) and write() execute concurrently the tx config might be modified while it is being copied to the fifo, resulting in potential data corruption. Fix: Get instance->tx_cfg_lock before modifying tx config in the PI433_IOC_WR_TX_CFG case in pi433_ioctl. Also, do not copy data directly from user space to instance->tx_cfg. Instead use a temporary buffer allowing future checks for correctness of copied data. Signed-off-by: Hugo Lefeuvre --- Changes in v2: - Use device->tx_fifo_lock instead of introducing a new lock in instance. - Do not copy data directly from user space to instance->tx_cfg, instead use a temporary buffer allowing future checks for correctness of copied data. --- drivers/staging/pi433/pi433_if.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/staging/pi433/pi433_if.c b/drivers/staging/pi433/pi433_if.c index b061f77dda41..3ec1ed01d04b 100644 --- a/drivers/staging/pi433/pi433_if.c +++ b/drivers/staging/pi433/pi433_if.c @@ -880,6 +880,7 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) int retval = 0; struct pi433_instance *instance; struct pi433_device *device; + struct pi433_tx_cfg tx_cfg_buffer; void __user *argp = (void __user *)arg; /* Check type and command number */ @@ -902,9 +903,15 @@ pi433_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) return -EFAULT; break; case PI433_IOC_WR_TX_CFG: - if (copy_from_user(&instance->tx_cfg, argp, - sizeof(struct pi433_tx_cfg))) + /* do not modify tx config while it is being copied to fifo */ + mutex_lock(&device->tx_fifo_lock); + if (copy_from_user(&tx_cfg_buffer, argp, + sizeof(struct pi433_tx_cfg))) { + mutex_unlock(&device->tx_fifo_lock); return -EFAULT; + } + memcpy(&instance->tx_cfg, &tx_cfg_buffer, sizeof(struct pi433_tx_cfg)); + mutex_unlock(&device->tx_fifo_lock); break; case PI433_IOC_RD_RX_CFG: if (copy_to_user(argp, &device->rx_cfg, -- 2.17.1