linux-kernel - Re: [PATCH v2] vdpa/mlx5: Fix mlx5_vdpa_get_config() endianness on big-endian machines

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <m34remjchz3recrui5zwhuthbwxl2fb5dcjzdhxuedrbsa6q5c@xshyty77q6ul>
Date: Tue, 4 Feb 2025 18:15:54 +0000
From: Dragos Tatulea <dtatulea@...dia.com>
To: Konstantin Shkolnyy <kshk@...ux.ibm.com>
Cc: virtualization@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	mjrosato@...ux.ibm.com, mst@...hat.com, jasowang@...hat.com
Subject: Re: [PATCH v2] vdpa/mlx5: Fix mlx5_vdpa_get_config() endianness on
 big-endian machines

On 02/04, Konstantin Shkolnyy wrote:
> mlx5_vdpa_dev_add() doesn’t initialize mvdev->actual_features. It’s
> initialized later by mlx5_vdpa_set_driver_features(). However,
> mlx5_vdpa_get_config() depends on the VIRTIO_F_VERSION_1 flag in
> actual_features, to return data with correct endianness. When it’s called
> before mlx5_vdpa_set_driver_features(), the data are incorrectly returned
> as big-endian on big-endian machines, while QEMU then interprets them as
> little-endian.
> 
> The fix is to initialize this VIRTIO_F_VERSION_1 as early as possible,
> especially considering that mlx5_vdpa_dev_add() insists on this flag to
> always be set anyway.
> 
> Signed-off-by: Konstantin Shkolnyy <kshk@...ux.ibm.com>
> ---
> Changes in V2: Initialize only VIRTIO_F_VERSION_1 in actual_features,
> rather than all flags.
> 
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 36099047560d..cccc49a08a1a 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -3884,6 +3884,9 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
>  	ndev->mvdev.max_vqs = max_vqs;
>  	mvdev = &ndev->mvdev;
>  	mvdev->mdev = mdev;
> +	/* cpu_to_mlx5vdpa16() below depends on this flag */
> +	mvdev->actual_features =
> +			(device_features & BIT_ULL(VIRTIO_F_VERSION_1));
>  
>  	ndev->vqs = kcalloc(max_vqs, sizeof(*ndev->vqs), GFP_KERNEL);
>  	ndev->event_cbs = kcalloc(max_vqs + 1, sizeof(*ndev->event_cbs), GFP_KERNEL);
> -- 
> 2.34.1
>
The patch looks good now. Thanks!

Reviewed-by: Dragos Tatulea <dtatulea@...dia.com>