diff --git a/MAINTAINERS b/MAINTAINERS
index 64c7169db617..37d664e505c6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18106,6 +18106,7 @@ S:	Maintained
 W:	http://vtun.sourceforge.net/tun
 F:	Documentation/networking/tuntap.rst
 F:	arch/um/os-Linux/drivers/
+F:	include/linux/tun_util.h
 
 TURBOCHANNEL SUBSYSTEM
 M:	"Maciej W. Rozycki" <macro@linux-mips.org>
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 978ac0981d16..6373c6f3416e 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -69,6 +69,7 @@
 #include <linux/bpf.h>
 #include <linux/bpf_trace.h>
 #include <linux/mutex.h>
+#include <linux/tun_util.h>
 
 #include <linux/uaccess.h>
 #include <linux/proc_fs.h>
@@ -3088,6 +3089,7 @@ static long __tun_chr_ioctl(struct file *file, unsigned int cmd,
 				break;
 			}
 			tun->dev->type = (int) arg;
+			tun->dev->addr_len = tun_get_addr_len(tun->dev->type);
 			netif_info(tun, drv, tun->dev, "linktype set to %d\n",
 				   tun->dev->type);
 			call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE,
diff --git a/include/linux/tun_util.h b/include/linux/tun_util.h
new file mode 100644
index 000000000000..daf11320cacc
--- /dev/null
+++ b/include/linux/tun_util.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _LINUX_TUN_UTIL_H
+#define _LINUX_TUN_UTIL_H
+
+#include <linux/ieee802154.h>
+#include <linux/if_ltalk.h>
+#include <uapi/linux/if_arp.h>
+#include <uapi/linux/if_fddi.h>
+#include <uapi/linux/if_hippi.h>
+#include <uapi/linux/if_fc.h>
+#include <net/ax25.h>
+#include <net/rose.h>
+#include <net/6lowpan.h>
+
+/*
+ * Intended for use within the tun driver, in order to correctly
+ * set tun->dev->addr_len during TUNSETLINK ioctl processing.
+ */
+static inline unsigned char tun_get_addr_len(unsigned short type)
+{
+	switch (type) {
+	case ARPHRD_IP6GRE:
+		fallthrough;
+	case ARPHRD_TUNNEL6:
+		return sizeof(struct in6_addr);
+	case ARPHRD_IPGRE:
+		fallthrough;
+	case ARPHRD_TUNNEL:
+		fallthrough;
+	case ARPHRD_SIT:
+		return 4;
+	case ARPHRD_ETHER:
+		return ETH_ALEN;
+	case ARPHRD_IEEE802154:
+		fallthrough;
+	case ARPHRD_IEEE802154_MONITOR:
+		return IEEE802154_EXTENDED_ADDR_LEN;
+	case ARPHRD_PHONET_PIPE:
+		fallthrough;
+	case ARPHRD_PPP:
+		fallthrough;
+	case ARPHRD_NONE:
+		return 0;
+	case ARPHRD_6LOWPAN:
+		return EUI64_ADDR_LEN;
+	case ARPHRD_FDDI:
+		return FDDI_K_ALEN;
+	case ARPHRD_HIPPI:
+		return HIPPI_ALEN;
+	case ARPHRD_IEEE802:
+		return FC_ALEN;
+	case ARPHRD_ROSE:
+		return ROSE_ADDR_LEN;
+	case ARPHRD_NETROM:
+		return AX25_ADDR_LEN;
+	case ARPHRD_LOCALTLK:
+		return LTALK_ALEN;
+	default:
+		return 0;
+	}
+}
+
+#endif