mctp i3c: handle NULL header address

daddr can be NULL if there is no neighbour table entry present,
in that case the tx packet should be dropped.

saddr will usually be set by MCTP core, but check for NULL in case a
packet is transmitted by a different protocol.

Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Fixes: c8755b29b58e ("mctp i3c: MCTP I3C driver")
Link: https://patch.msgid.link/20250304-mctp-i3c-null-v1-1-4416bbd56540@codeconstruct.com.au
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/mctp/mctp-i3c.c b/drivers/net/mctp/mctp-i3c.c
index d247fe483c588594c0dc92aa8e9c3c798d910d6b..c1e72253063b54a9c2ff9e45e6202347b8c962a7 100644 (file)
--- a/drivers/net/mctp/mctp-i3c.c
+++ b/drivers/net/mctp/mctp-i3c.c
@@ -507,6 +507,9 @@ static int mctp_i3c_header_create(struct sk_buff *skb, struct net_device *dev,
 {
        struct mctp_i3c_internal_hdr *ihdr;
 
+       if (!daddr || !saddr)
+               return -EINVAL;
+
        skb_push(skb, sizeof(struct mctp_i3c_internal_hdr));
        skb_reset_mac_header(skb);
        ihdr = (void *)skb_mac_header(skb);