[PATCH v2] tpm-dev-common: Reject too short writes
jarkko.sakkinen at linux.intel.com
Wed Sep 6 12:42:33 UTC 2017
On Mon, Sep 04, 2017 at 07:36:42PM +0200, Alexander Steffen wrote:
> tpm_transmit() does not offer an explicit interface to indicate the number
> of valid bytes in the communication buffer. Instead, it relies on the
> commandSize field in the TPM header that is encoded within the buffer.
> Therefore, ensure that a) enough data has been written to the buffer, so
> that the commandSize field is present and b) the commandSize field does not
> announce more data than has been written to the buffer.
> 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 at vger.kernel.org
> Signed-off-by: Alexander Steffen <Alexander.Steffen at infineon.com>
> - Moved all changes to tpm_common_write in a single patch.
> drivers/char/tpm/tpm-dev-common.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
> diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
> index 610638a..ac25574 100644
> --- a/drivers/char/tpm/tpm-dev-common.c
> +++ b/drivers/char/tpm/tpm-dev-common.c
> @@ -99,7 +99,8 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf,
> if (atomic_read(&priv->data_pending) != 0)
> return -EBUSY;
> - if (in_size > TPM_BUFSIZE)
> + if (in_size > sizeof(priv->data_buffer) || in_size < 6 ||
> + in_size < be32_to_cpu(*((__be32 *) (buf + 2))))
> return -E2BIG;
How did you test this change after you implemented it?
Just thinking what to add to https://github.com/jsakkine-intel/tpm2-scripts
To unsubscribe from this list: send the line "unsubscribe linux-security-module" in
the body of a message to majordomo at vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
More information about the Linux-security-module-archive