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Message-ID: <20170525224050.GA15715@obsidianresearch.com>
Date: Thu, 25 May 2017 16:40:50 -0600
From: Jason Gunthorpe <jgunthorpe@...idianresearch.com>
To: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc: tpmdd-devel@...ts.sourceforge.net,
linux-security-module@...r.kernel.org,
Peter Huewe <peterhuewe@....de>,
Marcel Selhorst <tpmdd@...horst.net>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH RFC] tpm: migrate pubek_show to struct tpm_buf
On Thu, May 25, 2017 at 03:28:01PM -0700, Jarkko Sakkinen wrote:
> On Thu, May 25, 2017 at 03:16:13PM -0600, Jason Gunthorpe wrote:
> > On Thu, May 25, 2017 at 02:11:04PM -0700, Jarkko Sakkinen wrote:
> > > struct tpm_chip *chip = to_tpm_chip(dev);
> > > + char anti_replay[20];
> > >
> > > - tpm_cmd.header.in = tpm_readpubek_header;
> > > - err = tpm_transmit_cmd(chip, NULL, &tpm_cmd, READ_PUBEK_RESULT_SIZE,
> > > + rc = tpm_buf_init(&tpm_buf, TPM_TAG_RQU_COMMAND, TPM_ORD_READPUBEK);
> > > + if (rc)
> > > + return rc;
> > > +
> > > + /* The checksum is ignored so it doesn't matter what the contents are.
> > > + */
> > > + tpm_buf_append(&tpm_buf, anti_replay, sizeof(anti_replay));
> >
> > It does matter, we do not want to leak random kernel memory incase it
> > has something sensitive. Zero anti_replay.
>
> If there was a leak it has existed before this change as tpm_cmd was
> also allocated from stack. And there is not leak because the checksum is
> not printed.
It leaks stack memory to the TPM which is not OK.
> I think better idea would be to move struct tpm_readpubek_params_out
> declaration here and use it to refer different fields. Previously
> this
That would be better..
Jason
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