RE: [PATCH] vdpa/mlx5: Fix pointer math in mlx5_vdpa_get_config()

[Eli Cohen]

Acked-by: Eli Cohen <elic@xxxxxxxxxx>

BTW, vdpa_sim has the same bug.

-----Original Message-----
From: Dan Carpenter <dan.carpenter@xxxxxxxxxx> 
Sent: Saturday, August 8, 2020 12:33 PM
To: Michael S. Tsirkin <mst@xxxxxxxxxx>; Eli Cohen <eli@xxxxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>; Parav Pandit <parav@xxxxxxxxxxxx>; virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; kernel-janitors@xxxxxxxxxxxxxxx
Subject: [PATCH] vdpa/mlx5: Fix pointer math in mlx5_vdpa_get_config()

There is a pointer math bug here so if "offset" is non-zero then this will copy memory from beyond the end of the array.

Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
 drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index 3ec44a4f0e45..9d1637cf772e 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -1758,7 +1758,7 @@ static void mlx5_vdpa_get_config(struct vdpa_device *vdev, unsigned int offset,
 	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
 
 	if (offset + len < sizeof(struct virtio_net_config))
-		memcpy(buf, &ndev->config + offset, len);
+		memcpy(buf, (u8 *)&ndev->config + offset, len);
 }
 
 static void mlx5_vdpa_set_config(struct vdpa_device *vdev, unsigned int offset, const void *buf,
--
2.27.0