[PATCH net-next] hv_netvsc: fix bogus ifalias on network device

[Stephen Hemminger <stephen@networkplumber.org>]

If the guest network adapter is not configured with DeviceNaming
enabled on the host, then the query for friendly name will return
success but with a zero length name. Which then leads to a garbage value
(stack contents) for ifalias.

Fix is simple, just don't set name if  host doesn't return it.

Fixes: 0fe554a46a0f ("hv_netvsc: propogate Hyper-V friendly name into interface alias")
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
---
 drivers/net/hyperv/rndis_filter.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 7f3dab4b4cbc..5428bb261102 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -1237,7 +1237,10 @@ static void rndis_get_friendly_name(struct net_device *net,
 	if (rndis_filter_query_device(rndis_device, net_device,
 				      RNDIS_OID_GEN_FRIENDLY_NAME,
 				      wname, &size) != 0)
-		return;
+		return;	/* ignore if host does not support */
+
+	if (size == 0)
+		return;	/* name not set */
 
 	/* Convert Windows Unicode string to UTF-8 */
 	len = ucs2_as_utf8(ifalias, wname, sizeof(ifalias));
-- 
2.17.0