From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49182 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729165AbeIYSUw (ORCPT ); Tue, 25 Sep 2018 14:20:52 -0400 Received: from pps.filterd (m0098421.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w8PC3vG8101778 for ; Tue, 25 Sep 2018 08:13:35 -0400 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0a-001b2d01.pphosted.com with ESMTP id 2mqjf46n6b-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Tue, 25 Sep 2018 08:13:34 -0400 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 25 Sep 2018 13:13:33 +0100 From: Halil Pasic To: Cornelia Huck , Halil Pasic , linux-s390@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org Cc: stable@vger.kernel.org, Colin Ian King , Christian Borntraeger Subject: [PATCH v2 1/2] virtio/s390: avoid race on vcdev->config Date: Tue, 25 Sep 2018 14:13:08 +0200 In-Reply-To: <20180925121309.58524-1-pasic@linux.ibm.com> References: <20180925121309.58524-1-pasic@linux.ibm.com> Message-Id: <20180925121309.58524-2-pasic@linux.ibm.com> Sender: stable-owner@vger.kernel.org List-ID: Currently we have a race on vcdev->config in virtio_ccw_get_config() and in virtio_ccw_set_config(). This normally does not cause problems, as these are usually infrequent operations. However, for some devices writing to/reading from the config space can be triggered through sysfs attributes. For these, userspace can force the race by increasing the frequency. Signed-off-by: Halil Pasic Cc: stable@vger.kernel.org --- drivers/s390/virtio/virtio_ccw.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index 8f5c1d7f751a..a5e8530a3391 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -828,6 +828,7 @@ static void virtio_ccw_get_config(struct virtio_device *vdev, int ret; struct ccw1 *ccw; void *config_area; + unsigned long flags; ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL); if (!ccw) @@ -846,11 +847,13 @@ static void virtio_ccw_get_config(struct virtio_device *vdev, if (ret) goto out_free; + spin_lock_irqsave(&vcdev->lock, flags); memcpy(vcdev->config, config_area, offset + len); - if (buf) - memcpy(buf, &vcdev->config[offset], len); if (vcdev->config_ready < offset + len) vcdev->config_ready = offset + len; + spin_unlock_irqrestore(&vcdev->lock, flags); + if (buf) + memcpy(buf, config_area + offset, len); out_free: kfree(config_area); @@ -864,6 +867,7 @@ static void virtio_ccw_set_config(struct virtio_device *vdev, struct virtio_ccw_device *vcdev = to_vc_device(vdev); struct ccw1 *ccw; void *config_area; + unsigned long flags; ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL); if (!ccw) @@ -876,9 +880,11 @@ static void virtio_ccw_set_config(struct virtio_device *vdev, /* Make sure we don't overwrite fields. */ if (vcdev->config_ready < offset) virtio_ccw_get_config(vdev, 0, NULL, offset); + spin_lock_irqsave(&vcdev->lock, flags); memcpy(&vcdev->config[offset], buf, len); /* Write the config area to the host. */ memcpy(config_area, vcdev->config, sizeof(vcdev->config)); + spin_unlock_irqrestore(&vcdev->lock, flags); ccw->cmd_code = CCW_CMD_WRITE_CONF; ccw->flags = 0; ccw->count = offset + len; -- 2.16.4