From 92054f4de90ba3730d73a0cbe97d8ab1543f7c3a Mon Sep 17 00:00:00 2001 From: Halil Pasic Date: Wed, 26 Sep 2018 18:48:29 +0200 Subject: virtio/s390: avoid race on vcdev->config commit 2448a299ec416a80f699940a86f4a6d9a4f643b1 upstream. 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 Message-Id: <20180925121309.58524-2-pasic@linux.ibm.com> Signed-off-by: Cornelia Huck Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman --- drivers/s390/virtio/virtio_ccw.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'drivers/s390/virtio/virtio_ccw.c') diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index 8688ad4c825f..92831aeea835 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -837,6 +837,7 @@ 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) @@ -855,11 +856,13 @@ 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); @@ -873,6 +876,7 @@ 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) @@ -885,9 +889,11 @@ 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; -- cgit v1.2.3 From 95e3e514c75284e77274e68f61e362004a120e72 Mon Sep 17 00:00:00 2001 From: Halil Pasic Date: Wed, 26 Sep 2018 18:48:30 +0200 Subject: virtio/s390: fix race in ccw_io_helper() commit 78b1a52e05c9db11d293342e8d6d8a230a04b4e7 upstream. While ccw_io_helper() seems like intended to be exclusive in a sense that it is supposed to facilitate I/O for at most one thread at any given time, there is actually nothing ensuring that threads won't pile up at vcdev->wait_q. If they do, all threads get woken up and see the status that belongs to some other request than their own. This can lead to bugs. For an example see: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1788432 This race normally does not cause any problems. The operations provided by struct virtio_config_ops are usually invoked in a well defined sequence, normally don't fail, and are normally used quite infrequent too. Yet, if some of the these operations are directly triggered via sysfs attributes, like in the case described by the referenced bug, userspace is given an opportunity to force races by increasing the frequency of the given operations. Let us fix the problem by ensuring, that for each device, we finish processing the previous request before starting with a new one. Signed-off-by: Halil Pasic Reported-by: Colin Ian King Cc: stable@vger.kernel.org Message-Id: <20180925121309.58524-3-pasic@linux.ibm.com> Signed-off-by: Cornelia Huck Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman --- drivers/s390/virtio/virtio_ccw.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'drivers/s390/virtio/virtio_ccw.c') diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index 92831aeea835..3493d449911c 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -59,6 +59,7 @@ struct virtio_ccw_device { unsigned int revision; /* Transport revision */ wait_queue_head_t wait_q; spinlock_t lock; + struct mutex io_lock; /* Serializes I/O requests */ struct list_head virtqueues; unsigned long indicators; unsigned long indicators2; @@ -307,6 +308,7 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev, unsigned long flags; int flag = intparm & VIRTIO_CCW_INTPARM_MASK; + mutex_lock(&vcdev->io_lock); do { spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags); ret = ccw_device_start(vcdev->cdev, ccw, intparm, 0, 0); @@ -319,7 +321,9 @@ static int ccw_io_helper(struct virtio_ccw_device *vcdev, cpu_relax(); } while (ret == -EBUSY); wait_event(vcdev->wait_q, doing_io(vcdev, flag) == 0); - return ret ? ret : vcdev->err; + ret = ret ? ret : vcdev->err; + mutex_unlock(&vcdev->io_lock); + return ret; } static void virtio_ccw_drop_indicator(struct virtio_ccw_device *vcdev, @@ -1239,6 +1243,7 @@ static int virtio_ccw_online(struct ccw_device *cdev) init_waitqueue_head(&vcdev->wait_q); INIT_LIST_HEAD(&vcdev->virtqueues); spin_lock_init(&vcdev->lock); + mutex_init(&vcdev->io_lock); spin_lock_irqsave(get_ccwdev_lock(cdev), flags); dev_set_drvdata(&cdev->dev, vcdev); -- cgit v1.2.3 From ffcad0a8f4ac3d8111cdea94cf50a5faa60ab161 Mon Sep 17 00:00:00 2001 From: Halil Pasic Date: Mon, 21 Jan 2019 13:19:43 +0100 Subject: s390/virtio: handle find on invalid queue gracefully commit 3438b2c039b4bf26881786a1f3450f016d66ad11 upstream. A queue with a capacity of zero is clearly not a valid virtio queue. Some emulators report zero queue size if queried with an invalid queue index. Instead of crashing in this case let us just return -ENOENT. To make that work properly, let us fix the notifier cleanup logic as well. Cc: stable@vger.kernel.org Signed-off-by: Halil Pasic Signed-off-by: Cornelia Huck Signed-off-by: Michael S. Tsirkin Signed-off-by: Greg Kroah-Hartman --- drivers/s390/virtio/virtio_ccw.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/s390/virtio/virtio_ccw.c') diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index 3493d449911c..d5e510ff5437 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -283,6 +283,8 @@ static void virtio_ccw_drop_indicators(struct virtio_ccw_device *vcdev) { struct virtio_ccw_vq_info *info; + if (!vcdev->airq_info) + return; list_for_each_entry(info, &vcdev->virtqueues, node) drop_airq_indicator(info->vq, vcdev->airq_info); } @@ -424,7 +426,7 @@ static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev, ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF); if (ret) return ret; - return vcdev->config_block->num; + return vcdev->config_block->num ?: -ENOENT; } static void virtio_ccw_del_vq(struct virtqueue *vq, struct ccw1 *ccw) -- cgit v1.2.3