diff --git a/net/core/filter.c b/net/core/filter.c
index 0ce93edefb0ed8ccc09b042200a726c14ee6bc4c..81bd2e9fe8fc710054ef2726bdb70b38dfdc2576 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4270,6 +4270,9 @@ BPF_CALL_4(bpf_xdp_fib_lookup, struct xdp_buff *, ctx,
 	if (plen < sizeof(*params))
 		return -EINVAL;
 
+	if (flags & ~(BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_OUTPUT))
+		return -EINVAL;
+
 	switch (params->family) {
 #if IS_ENABLED(CONFIG_INET)
 	case AF_INET:
@@ -4304,6 +4307,9 @@ BPF_CALL_4(bpf_skb_fib_lookup, struct sk_buff *, skb,
 	if (plen < sizeof(*params))
 		return -EINVAL;
 
+	if (flags & ~(BPF_FIB_LOOKUP_DIRECT | BPF_FIB_LOOKUP_OUTPUT))
+		return -EINVAL;
+
 	switch (params->family) {
 #if IS_ENABLED(CONFIG_INET)
 	case AF_INET: