On 2/11/21 3:37 PM, Dmitry Baryshkov wrote:
> Verify that user applications are not using the kernel RPC message
> handle to restrict them from directly attaching to guest OS on the
> remote subsystem. This is a port of CVE-2019-2308 fix.
>
> Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context Invoke method")
> Cc: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> Cc: Jonathan Marek <jonathan@xxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> ---
> drivers/misc/fastrpc.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 815d01f785df..e7f3a22fdaa3 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -948,6 +948,11 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl, u32 kernel,
> if (!fl->cctx->rpdev)
> return -EPIPE;
>
> + if (handle == FASTRPC_INIT_HANDLE && !kernel) {
> + dev_warn(fl->sctx->dev, "user app trying to send a kernel RPC message (%d)\n", handle);
rate limit so that userspace cannot flood kernel log?
> + return -EPERM;
> + }
> +
> ctx = fastrpc_context_alloc(fl, kernel, sc, args);
> if (IS_ERR(ctx))
> return PTR_ERR(ctx);
>
--
~Randy
