From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Zimmerman Subject: [PATCH] Check for error return values from get_burstcount. Date: Thu, 20 Oct 2016 17:21:29 -0700 Message-ID: <20161021002129.GA9464@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tpmdd-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Peter Huewe , Marcel Selhorst , Jarkko Sakkinen , Jason Gunthorpe , tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: tpmdd-devel@lists.sourceforge.net 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. --- drivers/char/tpm/tpm_tis_core.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index e3bf31b..d0301dc 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -186,6 +186,12 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count) chip->timeout_c, &priv->read_queue, true) == 0) { burstcnt = min_t(int, get_burstcount(chip), count - size); + if (burstcnt < 0) { + dev_err(&chip->dev, + "Unable to read burstcount in %s:%d (%s)\n", + __FILE__, __LINE__, __func__); + return rc; + } rc = tpm_tis_read_bytes(priv, TPM_DATA_FIFO(priv->locality), burstcnt, buf + size); @@ -272,6 +278,13 @@ 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); + if (burstcnt < 0) { + dev_err(&chip->dev, + "Unable to read burstcount in %s:%d (%s)\n", + __FILE__, __LINE__, __func__); + rc = burstcnt; + goto out_err; + } rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality), burstcnt, buf + count); if (rc < 0) -- 2.8.0.rc3.226.g39d4020 ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today. http://sdm.link/xeonphi