Re: [PATCH] tpm_tis: Check return values from get_burstcount.

[Greg KH <greg@kroah.com>]

On Mon, Jan 09, 2017 at 11:46:58PM +0200, Jarkko Sakkinen wrote:
> From: Josh Zimmerman <joshz@google.com>
> 
> 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: 1107d065fdf1 (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>
> ---
> Backport for 4.8 and 4.9

4.8 is now end-of-life, but I've queued this up for 4.9-stable, many
thanks!

greg k-h