tpm/tpm_i2c_stm_st33: Add status check when reading data on the FIFO

commit c4eadfaf upstream.

Add a return value check when reading data from the FIFO register.
Reviewed-by: Jason Gunthorpe <jason.gunthorpe@obsidianresearch.com>
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Reviewed-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/char/tpm/tpm_i2c_stm_st33.c

@@ -397,7 +397,7 @@ static int wait_for_stat(struct tpm_chip *chip, u8 mask, unsigned long timeout,
  */
 static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 {
-	int size = 0, burstcnt, len;
+	int size = 0, burstcnt, len, ret;
 	struct i2c_client *client;
 
 	client = (struct i2c_client *)TPM_VPRIV(chip);
@@ -412,7 +412,10 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
 		if (burstcnt < 0)
 			return burstcnt;
 		len = min_t(int, burstcnt, count - size);
-		I2C_READ_DATA(client, TPM_DATA_FIFO, buf + size, len);
+		ret = I2C_READ_DATA(client, TPM_DATA_FIFO, buf + size, len);
+		if (ret < 0)
+			return ret;
+
 		size += len;
 	}
 	return size;