From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>,
"Kenneth R. Crudup" <kenny@panix.com>,
Tyler Hicks <tyhicks@linux.microsoft.com>,
linux-integrity <linux-integrity@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>,
Matthew Garrett <mjg59@google.com>,
tweek@google.com
Subject: Re: [Regression] "tpm: Require that all digests are present in TCG_PCR_EVENT2 structures" causes null pointer dereference
Date: Mon, 28 Sep 2020 20:12:39 +0300 [thread overview]
Message-ID: <20200928171238.GB119268@linux.intel.com> (raw)
In-Reply-To: <CAMj1kXF-hOTZ62_Tf_GAN9_w7ztngdVp_atNrowH5Y0SwSjCAw@mail.gmail.com>
On Mon, Sep 28, 2020 at 06:15:00PM +0200, Ard Biesheuvel wrote:
> > > > It is possible but initially feels a bit weird:
> > > >
> > > > - sizeof(TCG_SPECID_SIG)) || count > efispecid->num_algs) {
> > > > + sizeof(TCG_SPECID_SIG)) ||
> > > > + !efispecid->num_algs || count != efispecid->num_algs) {
^^^
> In tpm2_bios_measurements_start(), we dereference tpm_bios_log to
> access bios_event_log and bios_event_log_end without checking tpm_bios
> for NULL. This is where the crash seems to occur.
That's a good guess. Just a bit confused how that particular patch can
have the effect: it has two deferences to efispecid instead of one in
the same statement. Would be interesting to hear if the bug is triggered
in Kenneth's environment by the exact same commit.
/Jarkko
next prev parent reply other threads:[~2020-09-28 17:12 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-28 12:31 [Regression] "tpm: Require that all digests are present in TCG_PCR_EVENT2 structures" causes null pointer dereference Kai-Heng Feng
2020-09-28 14:06 ` Jarkko Sakkinen
2020-09-28 14:16 ` Kai-Heng Feng
[not found] ` <20200928155215.GA92669@linux.intel.com>
2020-09-28 16:15 ` Ard Biesheuvel
2020-09-28 16:26 ` Ard Biesheuvel
2020-09-28 17:12 ` Jarkko Sakkinen [this message]
2020-09-28 18:05 ` Kenneth R. Crudup
2020-09-29 17:52 ` Mimi Zohar
2020-09-30 2:20 ` Jarkko Sakkinen
2020-10-08 9:09 ` Kai-Heng Feng
2020-10-09 16:06 ` Jarkko Sakkinen
2020-10-13 14:31 ` Tyler Hicks
2020-10-13 14:33 ` Jarkko Sakkinen
2020-10-20 21:07 ` Mimi Zohar
2020-10-21 5:48 ` Tyler Hicks
2020-10-26 5:49 ` Kai-Heng Feng
2020-10-27 5:08 ` Tyler Hicks
2020-10-28 15:41 ` [PATCH] tpm: efi: Don't create binary_bios_measurements file for an empty log Tyler Hicks
2020-10-28 16:30 ` Tyler Hicks
2020-10-28 17:39 ` Tyler Hicks
2020-10-30 6:41 ` Kai-Heng Feng
2020-11-04 2:12 ` Kenneth R. Crudup
2020-10-30 4:46 ` Jarkko Sakkinen
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