On Tue, Dec 7, 2021 at 7:49 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> In vduse_dev_ioctl(), the "config.offset" comes from the user. There
> needs to a check to prevent it being out of bounds. The "config.offset"
> and "dev->config_size" variables are both type u32. So if the offset is
> out of bounds then the "dev->config_size - config.offset" subtraction
> results in a very high u32 value.
>
> The vhost_vdpa_config_validate() function has a similar issue, but there
> the "size" is long type so the subtraction works on 64bit system and
> this change only affects 32bit systems.
>
> Fixes: c8a6153b6c59 ("vduse: Introduce VDUSE - vDPA Device in Userspace")
> Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Stable candidate.
Patch looks good to me but I think we need to use separate patches to
ease the backporting.
Thanks
> ---
> v2: the first version had a reversed if statement
> v3: fix vhost_vdpa_config_validate() as pointed out by Yongji Xie.
>
> drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++-
> drivers/vhost/vdpa.c | 2 +-
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
> index c9204c62f339..1a206f95d73a 100644
> --- a/drivers/vdpa/vdpa_user/vduse_dev.c
> +++ b/drivers/vdpa/vdpa_user/vduse_dev.c
> @@ -975,7 +975,8 @@ static long vduse_dev_ioctl(struct file *file, unsigned int cmd,
> break;
>
> ret = -EINVAL;
> - if (config.length == 0 ||
> + if (config.offset > dev->config_size ||
> + config.length == 0 ||
> config.length > dev->config_size - config.offset)
> break;
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 29cced1cd277..e3c4f059b21a 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -197,7 +197,7 @@ static int vhost_vdpa_config_validate(struct vhost_vdpa *v,
> struct vdpa_device *vdpa = v->vdpa;
> long size = vdpa->config->get_config_size(vdpa);
>
> - if (c->len == 0)
> + if (c->len == 0 || c->off > size)
> return -EINVAL;
>
> if (c->len > size - c->off)
> --
> 2.20.1
>
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