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SubjectRe: [PATCH RFC] tpm: migrate pubek_show to struct tpm_buf
On Thu, May 25, 2017 at 04:40:50PM -0600, Jason Gunthorpe wrote:
> 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.

Right, of course, vtpm_tpm_proxy.

/Jarkko

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