From: Sven Eckelmann <[email protected]>

Packets with a TTL are using it to limit the amount of time this packet can
be forwarded. But for batadv_frag_packet, the TTL was always only reduced
but it was never evaluated. It could even underflow without any effect.

Check the TTL in batadv_frag_skb_fwd() before attempting to prepare it for
forwarding. This keeps it in sync with the not fragmented unicast packet.

Cc: [email protected]
Fixes: 610bfc6bc99b ("batman-adv: Receive fragmented packets and merge")
Signed-off-by: Sven Eckelmann <[email protected]>
Signed-off-by: Simon Wunderlich <[email protected]>
---
 net/batman-adv/fragmentation.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/net/batman-adv/fragmentation.c b/net/batman-adv/fragmentation.c
index f311a42203d2e..8a006a0473a87 100644
--- a/net/batman-adv/fragmentation.c
+++ b/net/batman-adv/fragmentation.c
@@ -417,6 +417,13 @@ bool batadv_frag_skb_fwd(struct sk_buff *skb,
         */
        total_size = ntohs(packet->total_size);
        if (total_size > neigh_node->if_incoming->net_dev->mtu) {
+               if (packet->ttl < 2) {
+                       kfree_skb(skb);
+                       *rx_result = NET_RX_DROP;
+                       ret = true;
+                       goto out;
+               }
+
                if (skb_cow(skb, ETH_HLEN) < 0) {
                        kfree_skb(skb);
                        *rx_result = NET_RX_DROP;
-- 
2.47.3

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