On Wed, Dec 8, 2021 at 6:33 PM Dan Carpenter <dan.carpenter@xxxxxxxxxx> wrote:
>
> 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 if
> out of bounds then the "dev->config_size - config.offset" subtraction
> results in a very high u32 value. The out of bounds offset can result
> in memory corruption.
>
> Fixes: c8a6153b6c59 ("vduse: Introduce VDUSE - vDPA Device in Userspace")
> Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> v2: fix reversed if statement
> v3: fix vhost_vdpa_config_validate() as pointed out by Yongji Xie.
> v4: split the vhost_vdpa_config_validate() change into a separate path
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
>
> drivers/vdpa/vdpa_user/vduse_dev.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> 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;
>
> --
> 2.20.1
>
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