diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 7b4acd1ad991..8786b66c8a92 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -8,6 +8,7 @@
 #include "main.h"
 
 #include <linux/atomic.h>
+#include <linux/build_bug.h>
 #include <linux/byteorder/generic.h>
 #include <linux/compiler.h>
 #include <linux/errno.h>
@@ -204,6 +205,59 @@ bool batadv_check_management_packet(struct sk_buff *skb,
 	return true;
 }
 
+/**
+ * batadv_skb_decrement_ttl() - decrement ttl in a batman-adv header, csum-safe
+ * @skb: the received packet with @skb->data pointing to the batman-adv header
+ *
+ * Supports the following packet types, all of which carry the TTL at offset 2:
+ *
+ * - batadv_ogm_packet
+ * - batadv_ogm2_packet
+ * - batadv_icmp_header
+ * - batadv_icmp_packet
+ * - batadv_icmp_tp_packet
+ * - batadv_icmp_packet_rr
+ * - batadv_unicast_packet
+ * - batadv_frag_packet
+ * - batadv_bcast_packet
+ * - batadv_mcast_packet
+ * - batadv_coded_packet
+ * - batadv_unicast_tvlv_packet
+ *
+ * Return: true if the packet may be forwarded (ttl decremented),
+ *  false if it must be dropped (ttl would expire)
+ */
+static bool batadv_skb_decrement_ttl(struct sk_buff *skb)
+{
+	static const size_t ttl_offset = 2;
+	u8 *ttl_pos;
+
+	BUILD_BUG_ON(offsetof(struct batadv_ogm_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_ogm2_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_icmp_header, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_icmp_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_icmp_tp_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_icmp_packet_rr, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_unicast_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_frag_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_bcast_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_mcast_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_coded_packet, ttl) != ttl_offset);
+	BUILD_BUG_ON(offsetof(struct batadv_unicast_tvlv_packet, ttl) != ttl_offset);
+
+	ttl_pos = skb->data + ttl_offset;
+
+	/* would expire on this hop -> drop, leave header + csum untouched */
+	if (*ttl_pos < 2)
+		return false;
+
+	skb_postpull_rcsum(skb, ttl_pos, 1);
+	(*ttl_pos)--;
+	skb_postpush_rcsum(skb, ttl_pos, 1);
+
+	return true;
+}
+
 /**
  * batadv_recv_my_icmp_packet() - receive an icmp packet locally
  * @bat_priv: the bat priv with all the mesh interface information
@@ -1197,7 +1251,7 @@ int batadv_recv_bcast_packet(struct sk_buff *skb,
 
 	bcast_packet = (struct batadv_bcast_packet *)skb->data;
 
-	if (bcast_packet->ttl-- < 2)
+	if (!batadv_skb_decrement_ttl(skb))
 		goto free_skb;
 
 	orig_node = batadv_orig_hash_find(bat_priv, bcast_packet->orig);
@@ -1304,7 +1358,7 @@ int batadv_recv_mcast_packet(struct sk_buff *skb,
 		goto free_skb;
 
 	mcast_packet = (struct batadv_mcast_packet *)skb->data;
-	if (mcast_packet->ttl-- < 2)
+	if (!batadv_skb_decrement_ttl(skb))
 		goto free_skb;
 
 	tvlv_buff = (unsigned char *)(skb->data + hdr_size);