diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 4381e0fc25bf..84faace50ac2 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -608,14 +608,16 @@ EXPORT_SYMBOL_GPL(__netpoll_setup);
 /*
  * Returns a pointer to a string representation of the identifier used
  * to select the egress interface for the given netpoll instance. buf
- * must be a buffer of length at least MAC_ADDR_STR_LEN + 1.
+ * is used to format np->dev_mac when np->dev_name is empty; bufsz must
+ * be at least MAC_ADDR_STR_LEN + 1 to fit the formatted MAC address
+ * and its NUL terminator.
  */
-static char *egress_dev(struct netpoll *np, char *buf)
+static char *egress_dev(struct netpoll *np, char *buf, size_t bufsz)
 {
 	if (np->dev_name[0])
 		return np->dev_name;
 
-	snprintf(buf, MAC_ADDR_STR_LEN, "%pM", np->dev_mac);
+	snprintf(buf, bufsz, "%pM", np->dev_mac);
 	return buf;
 }
 
@@ -645,7 +647,7 @@ static int netpoll_take_ipv6(struct netpoll *np, struct net_device *ndev)
 
 	if (!IS_ENABLED(CONFIG_IPV6)) {
 		np_err(np, "IPv6 is not supported %s, aborting\n",
-		       egress_dev(np, buf));
+		       egress_dev(np, buf, sizeof(buf)));
 		return -EINVAL;
 	}
 
@@ -667,7 +669,7 @@ static int netpoll_take_ipv6(struct netpoll *np, struct net_device *ndev)
 	}
 	if (err) {
 		np_err(np, "no IPv6 address for %s, aborting\n",
-		       egress_dev(np, buf));
+		       egress_dev(np, buf, sizeof(buf)));
 		return err;
 	}
 
@@ -687,14 +689,14 @@ static int netpoll_take_ipv4(struct netpoll *np, struct net_device *ndev)
 	in_dev = __in_dev_get_rtnl(ndev);
 	if (!in_dev) {
 		np_err(np, "no IP address for %s, aborting\n",
-		       egress_dev(np, buf));
+		       egress_dev(np, buf, sizeof(buf)));
 		return -EDESTADDRREQ;
 	}
 
 	ifa = rtnl_dereference(in_dev->ifa_list);
 	if (!ifa) {
 		np_err(np, "no IP address for %s, aborting\n",
-		       egress_dev(np, buf));
+		       egress_dev(np, buf, sizeof(buf)));
 		return -EDESTADDRREQ;
 	}
 
@@ -736,7 +738,8 @@ int netpoll_setup(struct netpoll *np)
 		ndev = dev_getbyhwaddr(net, ARPHRD_ETHER, np->dev_mac);
 
 	if (!ndev) {
-		np_err(np, "%s doesn't exist, aborting\n", egress_dev(np, buf));
+		np_err(np, "%s doesn't exist, aborting\n",
+		       egress_dev(np, buf, sizeof(buf)));
 		err = -ENODEV;
 		goto unlock;
 	}
@@ -744,14 +747,14 @@ int netpoll_setup(struct netpoll *np)
 
 	if (netdev_master_upper_dev_get(ndev)) {
 		np_err(np, "%s is a slave device, aborting\n",
-		       egress_dev(np, buf));
+		       egress_dev(np, buf, sizeof(buf)));
 		err = -EBUSY;
 		goto put;
 	}
 
 	if (!netif_running(ndev)) {
 		np_info(np, "device %s not up yet, forcing it\n",
-			egress_dev(np, buf));
+			egress_dev(np, buf, sizeof(buf)));
 
 		err = dev_open(ndev, NULL);
 		if (err) {