diff --git a/drivers/i2c/i2c-stub.c b/drivers/i2c/i2c-stub.c
index fbb0db41b10e..04314e3ed24c 100644
--- a/drivers/i2c/i2c-stub.c
+++ b/drivers/i2c/i2c-stub.c
@@ -214,6 +214,11 @@ static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
 		 * We ignore banks here, because banked chips don't use I2C
 		 * block transfers
 		 */
+		if (data->block[0] == 0 ||
+		    data->block[0] > I2C_SMBUS_BLOCK_MAX) {
+			ret = -EINVAL;
+			break;
+		}
 		if (data->block[0] > 256 - command)	/* Avoid overrun */
 			data->block[0] = 256 - command;
 		len = data->block[0];