On 2020/10/23 下午11:34, Michael S. Tsirkin wrote:
On Fri, Oct 23, 2020 at 03:08:53PM +0300, Dan Carpenter wrote:
The copy_to/from_user() functions return the number of bytes which we
weren't able to copy but the ioctl should return -EFAULT if they fail.
Fixes: a127c5bbb6a8 ("vhost-vdpa: fix backend feature ioctls")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Needed for stable I guess.
Agree.
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/vhost/vdpa.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)
diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 62a9bb0efc55..c94a97b6bd6d 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -428,12 +428,11 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
void __user *argp = (void __user *)arg;
u64 __user *featurep = argp;
u64 features;
- long r;
+ long r = 0;
if (cmd == VHOST_SET_BACKEND_FEATURES) {
- r = copy_from_user(&features, featurep, sizeof(features));
- if (r)
- return r;
+ if (copy_from_user(&features, featurep, sizeof(features)))
+ return -EFAULT;
if (features & ~VHOST_VDPA_BACKEND_FEATURES)
return -EOPNOTSUPP;
vhost_set_backend_features(&v->vdev, features);
@@ -476,7 +475,8 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
break;
case VHOST_GET_BACKEND_FEATURES:
features = VHOST_VDPA_BACKEND_FEATURES;
- r = copy_to_user(featurep, &features, sizeof(features));
+ if (copy_to_user(featurep, &features, sizeof(features)))
+ r = -EFAULT;
break;
default:
r = vhost_dev_ioctl(&v->vdev, cmd, argp);
