On Sat, Sep 27, 2025 at 2:32 PM Michael S. Tsirkin [off-list ref] wrote:

On Sat, Sep 27, 2025 at 03:25:34PM +0300, Dan Carpenter wrote:

quoted

The group is supposed to be copied to the user, but it wasn't assigned
until after the copy_to_user().  Move the "s.num = group;" earlier.

Fixes: ffc3634b6696 ("vduse: add vq group support")
Signed-off-by: Dan Carpenter <redacted>
---
This goes through the kvm tree I think.

Thanks for the patch!

IIUC this was in my tree for next, but more testing
and review found issues (like this one) so I dropped it for now.

Yes, that's fixed in v5.

quoted

 drivers/vhost/vdpa.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 6305382eacbb..25ab4d06e559 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

@@ -667,9 +667,9 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
              group = ops->get_vq_group(vdpa, idx);
              if (group >= vdpa->ngroups || group > U32_MAX || group < 0)
                      return -EIO;
-             else if (copy_to_user(argp, &s, sizeof(s)))
-                     return -EFAULT;
              s.num = group;
+             if (copy_to_user(argp, &s, sizeof(s)))
+                     return -EFAULT;
              return 0;
      }
      case VHOST_VDPA_GET_VRING_DESC_GROUP:
--

2.51.0