linux-kernel - RE: [PATCH] vdpa/mlx5: Fix pointer math in mlx5_vdpa_get

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Date:   Sun, 9 Aug 2020 06:34:04 +0000
From:   Eli Cohen <elic@...dia.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        "Michael S. Tsirkin" <mst@...hat.com>, Eli Cohen <eli@...lanox.com>
CC:     Jason Wang <jasowang@...hat.com>,
        Parav Pandit <parav@...lanox.com>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: RE: [PATCH] vdpa/mlx5: Fix pointer math in mlx5_vdpa_get_config()

Acked-by: Eli Cohen <elic@...dia.com>

BTW, vdpa_sim has the same bug.

-----Original Message-----
From: Dan Carpenter <dan.carpenter@...cle.com> 
Sent: Saturday, August 8, 2020 12:33 PM
To: Michael S. Tsirkin <mst@...hat.com>; Eli Cohen <eli@...lanox.com>
Cc: Jason Wang <jasowang@...hat.com>; Parav Pandit <parav@...lanox.com>; virtualization@...ts.linux-foundation.org; linux-kernel@...r.kernel.org; kernel-janitors@...r.kernel.org
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@...cle.com>
---
 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