diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
index 699463bbfd2d..ac2305d8d7c4 100644
--- a/drivers/infiniband/core/uverbs_main.c
+++ b/drivers/infiniband/core/uverbs_main.c
@@ -668,6 +668,9 @@ static ssize_t ib_uverbs_write(struct file *filp, const char __user *buf,
 		if ((hdr.in_words + ex_hdr.provider_in_words) * 8 != count)
 			return -EINVAL;
 
+		if (ex_hdr.cmd_hdr_reserved)
+			return -EINVAL;
+
 		if (ex_hdr.response) {
 			if (!hdr.out_words && !ex_hdr.provider_out_words)
 				return -EINVAL;