[RFC PATCH] vhost-vdpa: mark vhost device invalid to reflect vdpa device unregistration
From: <hidden>
Date: 2021-07-04 20:52:48
From: Gautam Dawar <redacted> As mentioned in Bug 213179, any malicious user-space application can render a module registering a vDPA device to hang forever. This will typically surface when vdpa_device_unregister() is called from the function responsible for module unload, leading rmmod commands to not return. This patch unblocks the caller module by continuing with the clean-up but after marking the vhost device as unavailable. For future requests from user-space application, the vhost device availability is checked first and if it has gone unavailable, such requests are denied. Signed-off-by: Gautam Dawar <redacted> --- drivers/vhost/vdpa.c | 45 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 39 insertions(+), 6 deletions(-)
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index e4b7d26649d8..623bc7f0c0ca 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c@@ -47,6 +47,7 @@ struct vhost_vdpa { int minor; struct eventfd_ctx *config_ctx; int in_batch; + int dev_invalid; struct vdpa_iova_range range; };
@@ -61,6 +62,11 @@ static void handle_vq_kick(struct vhost_work *work) struct vhost_vdpa *v = container_of(vq->dev, struct vhost_vdpa, vdev); const struct vdpa_config_ops *ops = v->vdpa->config; + if (v->dev_invalid) { + dev_info(&v->dev, + "%s: vhost_vdpa device unavailable\n", __func__); + return; + } ops->kick_vq(v->vdpa, vq - v->vqs); }
@@ -120,6 +126,11 @@ static void vhost_vdpa_reset(struct vhost_vdpa *v) { struct vdpa_device *vdpa = v->vdpa; + if (v->dev_invalid) { + dev_info(&v->dev, + "%s: vhost_vdpa device unavailable\n", __func__); + return; + } vdpa_reset(vdpa); v->in_batch = 0; }
@@ -367,6 +378,11 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, u32 idx; long r; + if (v->dev_invalid) { + dev_info(&v->dev, + "%s: vhost_vdpa device unavailable\n", __func__); + return -ENODEV; + } r = get_user(idx, (u32 __user *)argp); if (r < 0) return r;
@@ -450,6 +466,11 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep, return 0; } + if (v->dev_invalid) { + dev_info(&v->dev, + "%s: vhost_vdpa device unavailable\n", __func__); + return -ENODEV; + } mutex_lock(&d->mutex); switch (cmd) {
@@ -745,8 +766,13 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, const struct vdpa_config_ops *ops = vdpa->config; int r = 0; - mutex_lock(&dev->mutex); + if (v->dev_invalid) { + dev_info(&v->dev, + "%s: vhost_vdpa device unavailable\n", __func__); + return -ENODEV; + } + mutex_lock(&dev->mutex); r = vhost_dev_check_owner(dev); if (r) goto unlock;
@@ -949,6 +975,11 @@ static vm_fault_t vhost_vdpa_fault(struct vm_fault *vmf) struct vm_area_struct *vma = vmf->vma; u16 index = vma->vm_pgoff; + if (v->dev_invalid) { + dev_info(&v->dev, + "%s: vhost_vdpa device unavailable\n", __func__); + return VM_FAULT_NOPAGE; + } notify = ops->get_vq_notification(vdpa, index); vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
@@ -1091,11 +1122,13 @@ static void vhost_vdpa_remove(struct vdpa_device *vdpa) opened = atomic_cmpxchg(&v->opened, 0, 1); if (!opened) break; - wait_for_completion_timeout(&v->completion, - msecs_to_jiffies(1000)); - dev_warn_once(&v->dev, - "%s waiting for /dev/%s to be closed\n", - __func__, dev_name(&v->dev)); + if (!wait_for_completion_timeout(&v->completion, + msecs_to_jiffies(1000))) { + dev_warn(&v->dev, + "%s /dev/%s in use, continue..\n", + __func__, dev_name(&v->dev)); + break; + } } while (1); put_device(&v->dev); + v->dev_invalid = true;
--
2.30.1