tpmdd-devel.lists.sourceforge.net archive mirror
 help / color / mirror / Atom feed
From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Alexander Steffen <Alexander.Steffen@infineon.com>
Cc: tpmdd-devel@lists.sourceforge.net, stable@vger.kernel.org
Subject: Re: [PATCH RESEND 1/2] tpm-dev-common: Reject too short writes
Date: Fri, 25 Aug 2017 19:54:51 +0300	[thread overview]
Message-ID: <20170825165451.b7lv7t5w3nhbz7da@linux.intel.com> (raw)
In-Reply-To: <20170824083545.13280-2-Alexander.Steffen@infineon.com>

On Thu, Aug 24, 2017 at 10:35:44AM +0200, Alexander Steffen wrote:
> tpm_common_write() in tpm-dev-common.c discards the information how much
> data has actually been written to the buffer. Instead, all other code has
> to rely on the commandSize field in the TPM command header to figure out
> how many valid bytes are supposed to be in the buffer.
> 
> But there is nothing that enforces the value in the header to match the
> actual buffer contents. So by claiming a larger size in the header than
> has been written, stale buffer contents are sent to the TPM. With this
> commit, this problem is detected and rejected accordingly.
> 
> This should have been fixed with CVE-2011-1161 long ago, but apparently
> a correct version of that patch never made it into the kernel.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
> ---
>  drivers/char/tpm/tpm-dev-common.c | 2 +-
>  drivers/char/tpm/tpm-interface.c  | 9 ++++++---
>  drivers/char/tpm/tpm.h            | 3 ++-
>  3 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
> index 610638a..c39b581 100644
> --- a/drivers/char/tpm/tpm-dev-common.c
> +++ b/drivers/char/tpm/tpm-dev-common.c
> @@ -119,7 +119,7 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
>  		return -EPIPE;
>  	}
>  	out_size = tpm_transmit(priv->chip, space, priv->data_buffer,
> -				sizeof(priv->data_buffer), 0);
> +				sizeof(priv->data_buffer), in_size, 0);

Why you couldn't just

unsigned int bufsiz;

/* ... */

bufsiz = sizeof(priv->data_buffer);
if (in_size < bufsiz)
	bufsiz = in_size;

out_size = tpm_transmit(priv->chip, space, priv->data_buffer, bufsiz, 0);

/Jarkko

  reply	other threads:[~2017-08-25 16:54 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-08-24  8:35 [PATCH RESEND 0/2] Avoid sending invalid data to the TPM Alexander Steffen
     [not found] ` <20170824083545.13280-1-Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w@public.gmane.org>
2017-08-24  8:35   ` [PATCH RESEND 1/2] tpm-dev-common: Reject too short writes Alexander Steffen
2017-08-25 16:54     ` Jarkko Sakkinen [this message]
     [not found]       ` <20170825165451.b7lv7t5w3nhbz7da-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-08-28 17:11         ` Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w
2017-08-30 10:40           ` Jarkko Sakkinen
2017-09-04 17:35             ` Alexander.Steffen
     [not found]               ` <dd865ba5751e4d568709e0aaf209633b-nFblLGNE8XKJSz+rYg/bSJowlv4uC7bZ@public.gmane.org>
2017-09-05 19:02                 ` Jarkko Sakkinen
2017-08-24  8:35   ` [PATCH RESEND 2/2] tpm-interface: Fix checks of buffer size Alexander Steffen
2017-08-25 16:44   ` [PATCH RESEND 0/2] Avoid sending invalid data to the TPM Jarkko Sakkinen
     [not found]     ` <20170825164416.svo7khm4zsmosxbx-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2017-09-01 12:08       ` Alexander.Steffen-d0qZbvYSIPpWk0Htik3J/w

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170825165451.b7lv7t5w3nhbz7da@linux.intel.com \
    --to=jarkko.sakkinen@linux.intel.com \
    --cc=Alexander.Steffen@infineon.com \
    --cc=stable@vger.kernel.org \
    --cc=tpmdd-devel@lists.sourceforge.net \
    --subject='Re: [PATCH RESEND 1/2] tpm-dev-common: Reject too short writes' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).