From b9885692cb283a674e04528486984fb61f92a190 Mon Sep 17 00:00:00 2001
From: Chris Leech <cleech@redhat.com>
Date: Tue, 23 Mar 2021 11:21:17 -0700
Subject: [PATCH] fix VLAN device name overflow check

check snprintf return for truncation

Signed-off-by: Chris Leech <cleech@redhat.com>
---
 fipvlan.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/fipvlan.c b/fipvlan.c
index fe8d7955cc5..3ce913d5eaf 100644
--- a/fipvlan.c
+++ b/fipvlan.c
@@ -624,8 +624,16 @@ create_and_start_vlan(struct fcf *fcf, bool vn2vn)
 				    real_dev->ifname, fcf->vlan, vlan->ifname);
 			rc = 0;
 		} else {
-			snprintf(vlan_name, IFNAMSIZ, "%s.%d%s",
-				 real_dev->ifname, fcf->vlan, config.suffix);
+			rc = snprintf(vlan_name, IFNAMSIZ, "%s.%d%s",
+					real_dev->ifname, fcf->vlan,
+					config.suffix);
+			if (rc < 0 || rc >= IFNAMSIZ) {
+				printf("Failed to create VLAN device "
+					"(name %s.%d%s is too long)\n",
+					real_dev->ifname, fcf->vlan,
+					config.suffix);
+				return -EINVAL;
+			}
 			rc = vlan_create(fcf->ifindex, fcf->vlan, vlan_name);
 			if (rc < 0)
 				printf("Failed to create VLAN device %s\n\t%s\n",