Messages in this thread | | | From | "Winkler, Tomas" <> | Subject | RE: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv() | Date | Tue, 5 Feb 2019 14:56:02 +0000 |
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> -----Original Message----- > From: Jarkko Sakkinen [mailto:jarkko.sakkinen@linux.intel.com] > Sent: Tuesday, February 05, 2019 16:36 > To: Winkler, Tomas <tomas.winkler@intel.com> > Cc: linux-integrity@vger.kernel.org; linux-kernel@vger.kernel.org; linux- > security-module@vger.kernel.org; stable@vger.kernel.org; James Morris > <jmorris@namei.org>; Jerry Snitselaar <jsnitsel@redhat.com> > Subject: Re: [PATCH v3] tpm/tpm_crb: Avoid unaligned reads in crb_recv() > > On Tue, Feb 05, 2019 at 11:07:16AM +0000, Winkler, Tomas wrote: > > > The current approach to read first 6 bytes from the response and > > > then tail of the response, can cause the 2nd memcpy_fromio() to do > > > an unaligned read (e.g. read 32-bit word from address aligned to a > > > 16-bits), depending on how > > > memcpy_fromio() is implemented. If this happens, the read will fail > > > and the memory controller will fill the read with 1's. > > > > > > This was triggered by 170d13ca3a2f, which should be probably refined > > > to check and react to the address alignment. Before that commit, on > > > x86 > > > memcpy_fromio() turned out to be memcpy(). By a luck GCC has done > > > the right thing (from tpm_crb's perspective) for us so far, but we should not > rely on that. > > > Thus, it makes sense to fix this also in tpm_crb, not least because > > > the fix can be then backported to stable kernels and make them more > > > robust when compiled in differing environments. > > > > > > Cc: stable@vger.kernel.org > > > Cc: James Morris <jmorris@namei.org> > > > Cc: Tomas Winkler <tomas.winkler@intel.com> > > > Cc: Jerry Snitselaar <jsnitsel@redhat.com> > > > Fixes: 30fc8d138e91 ("tpm: TPM 2.0 CRB Interface") > > > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> > > > Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com> > > > --- > > > v3: > > > * Fix typo i.e. %s/reminding/remaining/g > > > > Why you haven't fixed all the typos I've pointed out? I think you missed that. > > I saw only comment about remaining. Was there something else? Can fix.
https://www.spinics.net/lists/stable/msg283648.html
1. unrecovable -> unrecoverable 2. /* Read 8 bytes (not just 6 bytes, which would cover the tag and the response length > + * fields) in order to make sure that the remaining memory accesses */ Thanks Tomas
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