diff --git a/drivers/i2c/busses/i2c-ismt.c b/drivers/i2c/busses/i2c-ismt.c
index af2c240e064e..483428c5e30b 100644
--- a/drivers/i2c/busses/i2c-ismt.c
+++ b/drivers/i2c/busses/i2c-ismt.c
@@ -528,6 +528,9 @@ static int ismt_access(struct i2c_adapter *adap, u16 addr,
 
 	case I2C_SMBUS_BLOCK_PROC_CALL:
 		dev_dbg(dev, "I2C_SMBUS_BLOCK_PROC_CALL\n");
+		if (data->block[0] > I2C_SMBUS_BLOCK_MAX)
+			return -EINVAL;
+
 		dma_size = I2C_SMBUS_BLOCK_MAX;
 		desc->tgtaddr_rw = ISMT_DESC_ADDR_RW(addr, 1);
 		desc->wr_len_cmd = data->block[0] + 1;