diff --git a/drivers/sbus/char/oradax.c b/drivers/sbus/char/oradax.c
index 03dc04739225..c44d7c7ffc92 100644
--- a/drivers/sbus/char/oradax.c
+++ b/drivers/sbus/char/oradax.c
@@ -880,7 +880,7 @@ static int dax_ccb_exec(struct dax_ctx *ctx, const char __user *buf,
 	dax_dbg("args: ccb_buf_len=%ld, idx=%d", count, idx);
 
 	/* for given index and length, verify ca_buf range exists */
-	if (idx + nccbs >= DAX_CA_ELEMS) {
+	if (idx < 0 || idx > (DAX_CA_ELEMS - nccbs)) {
 		ctx->result.exec.status = DAX_SUBMIT_ERR_NO_CA_AVAIL;
 		return 0;
 	}