nfp: bpf: Add check for nfp_app_ctrl_msg_alloc()

Add check for the return value of nfp_app_ctrl_msg_alloc() in
nfp_bpf_cmsg_alloc() to prevent null pointer dereference.

Fixes: ff3d43f ("nfp: bpf: implement helpers for FW map ops")
Cc: stable@vger.kernel.org
Signed-off-by: Haoxiang Li <haoxiang_li2024@163.com>
Link: https://patch.msgid.link/20250218030409.2425798-1-haoxiang_li2024@163.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/netronome/nfp/bpf/cmsg.c

@@ -20,6 +20,8 @@ nfp_bpf_cmsg_alloc(struct nfp_app_bpf *bpf, unsigned int size)
 	struct sk_buff *skb;
 
 	skb = nfp_app_ctrl_msg_alloc(bpf->app, size, GFP_KERNEL);
+	if (!skb)
+		return NULL;
 	skb_put(skb, size);
 
 	return skb;