[PATCH net v2 5/8] net: rmnet: do not allow to change mux id if mux id is duplicated

[PATCH net v2 5/8] net: rmnet: do not allow to change mux id if mux id is duplicated

[Taehee Yoo]

Basically, duplicate mux id isn't be allowed.
So, the creation of rmnet will be failed if there is duplicate mux id
is existing.
But, changelink routine doesn't check duplicate mux id.

Test commands:
    modprobe rmnet
    ip link add dummy0 type dummy
    ip link add rmnet0 link dummy0 type rmnet mux_id 1
    ip link add rmnet1 link dummy0 type rmnet mux_id 2
    ip link set rmnet1 type rmnet mux_id 1

Fixes: 23790ef12082 ("net: qualcomm: rmnet: Allow to configure flags for existing devices")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
---

v1 -> v2:
  - update commit log.

 drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
index 0ad64aa66592..3c0e6d24d083 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
@@ -306,6 +306,10 @@ static int rmnet_changelink(struct net_device *dev, struct nlattr *tb[],
 
 	if (data[IFLA_RMNET_MUX_ID]) {
 		mux_id = nla_get_u16(data[IFLA_RMNET_MUX_ID]);
+		if (rmnet_get_endpoint(port, mux_id)) {
+			NL_SET_ERR_MSG_MOD(extack, "MUX ID already exists");
+			return -EINVAL;
+		}
 		ep = rmnet_get_endpoint(port, priv->mux_id);
 		if (!ep)
 			return -ENODEV;
-- 
2.17.1