From e4b52c7cbaaf4d11288d331b654b0fac450e4971 Mon Sep 17 00:00:00 2001 From: Dmitry Baryshkov Date: Fri, 12 Feb 2021 22:26:58 +0300 Subject: [PATCH] misc: fastrpc: restrict user apps from sending kernel RPC messages commit 20c40794eb85ea29852d7bc37c55713802a543d6 upstream. 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 Cc: Jonathan Marek Cc: stable@vger.kernel.org Signed-off-by: Dmitry Baryshkov Link: https://lore.kernel.org/r/20210212192658.3476137-1-dmitry.baryshkov@linaro.org Signed-off-by: Greg Kroah-Hartman --- drivers/misc/fastrpc.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 3a5d2890fe2a..beaf15807f78 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -924,6 +924,11 @@ 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_ratelimited(fl->sctx->dev, "user app trying to send a kernel RPC message (%d)\n", handle); + return -EPERM; + } + ctx = fastrpc_context_alloc(fl, kernel, sc, args); if (IS_ERR(ctx)) return PTR_ERR(ctx);