The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to [off-list ref].

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From cd025c1e876b4e262e71398236a1550486a73ede Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= <eperezma@redhat.com>
Date: Mon, 19 Jan 2026 15:32:54 +0100
Subject: [PATCH] vhost: move vdpa group bound check to vhost_vdpa
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Remove duplication by consolidating these here.  This reduces the
posibility of a parent driver missing them.

While we're at it, fix a bug in vdpa_sim where a valid ASID can be
assigned to a group equal to ngroups, causing an out of bound write.

Cc: stable@vger.kernel.org
Fixes: bda324fd037a ("vdpasim: control virtqueue support")
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: [off-list ref]
---
 drivers/vdpa/mlx5/net/mlx5_vnet.c | 3 ---
 drivers/vdpa/vdpa_sim/vdpa_sim.c  | 6 ------
 drivers/vhost/vdpa.c              | 2 +-
 3 files changed, 1 insertion(+), 10 deletions(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index ddaa1366704bb..44062e9d68f00 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c

@@ -3640,9 +3640,6 @@ static int mlx5_set_group_asid(struct vdpa_device *vdev, u32 group,
 	struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
 	int err = 0;
 
-	if (group >= MLX5_VDPA_NUMVQ_GROUPS)
-		return -EINVAL;
-
 	mvdev->mres.group2asid[group] = asid;
 
 	mutex_lock(&mvdev->mres.lock);

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index c1c6431950e1b..df9c7ddc5d782 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c

@@ -606,12 +606,6 @@ static int vdpasim_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
 	struct vhost_iotlb *iommu;
 	int i;
 
-	if (group > vdpasim->dev_attr.ngroups)
-		return -EINVAL;
-
-	if (asid >= vdpasim->dev_attr.nas)
-		return -EINVAL;
-
 	iommu = &vdpasim->iommu[asid];
 
 	mutex_lock(&vdpasim->mutex);

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 05a481e4c385a..9d25b735b43dd 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

@@ -680,7 +680,7 @@ static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
 	case VHOST_VDPA_SET_GROUP_ASID:
 		if (copy_from_user(&s, argp, sizeof(s)))
 			return -EFAULT;
-		if (s.num >= vdpa->nas)
+		if (idx >= vdpa->ngroups || s.num >= vdpa->nas)
 			return -EINVAL;
 		if (!ops->set_group_asid)
 			return -EOPNOTSUPP;

-- 
2.51.0