From: Taehee Yoo <ap420073@gmail.com>
Date: Tue, 7 Apr 2020 13:23:21 +0000
Subject: hsr: check protocol version in hsr_newlink()
Git-commit: 4faab8c446def7667adf1f722456c2f4c304069c
Patch-mainline: 5.7-rc2
References: networking-stable-20_04_17

In the current hsr code, only 0 and 1 protocol versions are valid.
But current hsr code doesn't check the version, which is received by
userspace.

Test commands:
    ip link add dummy0 type dummy
    ip link add dummy1 type dummy
    ip link add hsr0 type hsr slave1 dummy0 slave2 dummy1 version 4

In the test commands, version 4 is invalid.
So, the command should be failed.

After this patch, following error will occur.
"Error: hsr: Only versions 0..1 are supported."

Fixes: ee1c27977284 ("net/hsr: Added support for HSR v1")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/hsr/hsr_netlink.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

--- a/net/hsr/hsr_netlink.c
+++ b/net/hsr/hsr_netlink.c
@@ -64,10 +64,16 @@ static int hsr_newlink(struct net *src_n
 	else
 		multicast_spec = nla_get_u8(data[IFLA_HSR_MULTICAST_SPEC]);
 
-	if (!data[IFLA_HSR_VERSION])
+	if (!data[IFLA_HSR_VERSION]) {
 		hsr_version = 0;
-	else
+	} else {
 		hsr_version = nla_get_u8(data[IFLA_HSR_VERSION]);
+		if (hsr_version > 1) {
+			NL_SET_ERR_MSG_MOD(extack,
+					   "Only versions 0..1 are supported");
+			return -EINVAL;
+		}
+	}
 
 	return hsr_dev_finalize(dev, link, multicast_spec, hsr_version);
 }