linux-kernel - Re: [tpmdd-devel] [PATCH RFC 2/4] tpm: validate TPM 2.0 commands

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Message-ID: <20170104184422.GA12283@obsidianresearch.com>
Date:   Wed, 4 Jan 2017 11:44:22 -0700
From:   Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To:     Stefan Berger <stefanb@...ibm.com>
Cc:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-security-module@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [tpmdd-devel] [PATCH RFC 2/4] tpm: validate TPM 2.0 commands

On Wed, Jan 04, 2017 at 01:04:59PM -0500, Stefan Berger wrote:

>    > @@ -943,7 +943,9 @@ EXPORT_SYMBOL_GPL(tpm2_probe);
>    >   */
>    >  int tpm2_auto_startup(struct tpm_chip *chip)
>    >  {
>    > +   u32 nr_commands;
>    >     int rc;
>    > +   int i;
>    >
>    >     rc = tpm_get_timeouts(chip);
>    >     if (rc)
>    > @@ -967,8 +969,49 @@ int tpm2_auto_startup(struct tpm_chip *chip)
>    >        }
>    >     }
>    >
>    > +   rc = tpm2_get_tpm_pt(chip, TPM_PT_TOTAL_COMMANDS, &nr_commands,
>    NULL);
>    > +   if (rc)
>    > +      return rc;
>    > +
>    > +   chip->cc_attrs_tbl = devm_kzalloc(&chip->dev, 4 * nr_commands,
>    > +                 GFP_KERNEL);
>    For some reason this devm_kzalloc bombs for the vtpm proxy driver. The
>    only reason I could come up with is that it's being called before
>    tpm_add_char_device() has been called.

It would also fail if nr_commands is wrong, and this should be one of
the array safe allocation functions since nr_command is data from the
TPM...

Jason