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tpm_tis: Check return values from get_burstcount.

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If the TPM we're connecting to uses a static burst count, it will report
a burst count of zero throughout the response read. However, get_burstcount
assumes that a response of zero indicates that the TPM is not ready to
receive more data. In this case, it returns a negative error code, which
is passed on to tpm_tis_{write,read}_bytes as a u16, causing
them to read/write far too many bytes.

This patch checks for negative return codes and bails out from recv_data
and tpm_tis_send_data.

Cc: stable@vger.kernel.org
Fixes: 1107d065fd (tpm_tis: Introduce intermediate layer for TPM access)
Signed-off-by: Josh Zimmerman <joshz@google.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
This commit is contained in:
Josh Zimmerman 2016-10-27 14:50:09 -07:00 committed by Jarkko Sakkinen
parent ca6d458022
commit 26a137e31f
1 changed files with 13 additions and 2 deletions
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15
drivers/char/tpm/tpm_tis_core.c
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@ -187,7 +187,12 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count)
&priv->read_queue, true);
if (rc < 0)
return rc;
burstcnt = min_t(int, get_burstcount(chip), count - size);
burstcnt = get_burstcount(chip);
if (burstcnt < 0) {
dev_err(&chip->dev, "Unable to read burstcount\n");
return burstcnt;
}
burstcnt = min_t(int, burstcnt, count - size);
rc = tpm_tis_read_bytes(priv, TPM_DATA_FIFO(priv->locality),
burstcnt, buf + size);
@ -276,7 +281,13 @@ static int tpm_tis_send_data(struct tpm_chip *chip, u8 *buf, size_t len)
}
while (count < len - 1) {
burstcnt = min_t(int, get_burstcount(chip), len - count - 1);
burstcnt = get_burstcount(chip);
if (burstcnt < 0) {
dev_err(&chip->dev, "Unable to read burstcount\n");
rc = burstcnt;
goto out_err;
}
burstcnt = min_t(int, burstcnt, len - count - 1);
rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality),
burstcnt, buf + count);
if (rc < 0)