From 5853193103e6e3be983cc86d61b204ed27a22716 Mon Sep 17 00:00:00 2001
From: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Date: Fri, 9 Aug 2019 08:40:19 +0100
Subject: [PATCH] um: Add checks to mtu parameter parsing

Adds a sanity check to the parsing of mtu command line param

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 arch/um/drivers/vector_kern.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index 8fa094770965..45ec9bc2430f 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -121,7 +121,8 @@ static int get_mtu(struct arglist *def)
 
 	if (mtu != NULL) {
 		if (kstrtoul(mtu, 10, &result) == 0)
-			return result;
+			if ((result < (1 << 16) - 1) && (result >= 576))
+				return result;
 	}
 	return ETH_MAX_PACKET;
 }