i2c: core-smbus: prevent stack corruption on read I2C_BLOCK_DATA
[pandora-kernel.git] / drivers / i2c / i2c-core.c
index c3793a7..8d96a47 100644 (file)
@@ -2009,16 +2009,17 @@ static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
                                   the underlying bus driver */
                break;
        case I2C_SMBUS_I2C_BLOCK_DATA:
+               if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
+                       dev_err(&adapter->dev, "Invalid block %s size %d\n",
+                               read_write == I2C_SMBUS_READ ? "read" : "write",
+                               data->block[0]);
+                       return -EINVAL;
+               }
+
                if (read_write == I2C_SMBUS_READ) {
                        msg[1].len = data->block[0];
                } else {
                        msg[0].len = data->block[0] + 1;
-                       if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
-                               dev_err(&adapter->dev,
-                                       "Invalid block write size %d\n",
-                                       data->block[0]);
-                               return -EINVAL;
-                       }
                        for (i = 1; i <= data->block[0]; i++)
                                msgbuf0[i] = data->block[i];
                }