Thread (9 messages) 9 messages, 3 authors, 2017-05-24

[tpmdd-devel] [PATCH] tpm: fix byte order related arithmetic inconsistency in tpm_getcap()

From: Jarkko Sakkinen <hidden>
Date: 2017-05-15 11:36:08
Also in: lkml

On Wed, May 10, 2017 at 03:34:58PM +0300, Jarkko Sakkinen wrote:
On Tue, May 09, 2017 at 09:13:08AM -0600, Jason Gunthorpe wrote:
quoted
On Tue, May 09, 2017 at 05:13:53PM +0300, Jarkko Sakkinen wrote:
quoted
On Sun, May 07, 2017 at 08:50:02PM +0300, Jarkko Sakkinen wrote:
quoted
You should not do arithmetic with __be32 or __le32 types because
sometimes it results incorrect results. Calculations must be done only
with integers that are in in the CPU byte order. This commit migrates
tpm_getcap() to struct tpm_buf in order to sort out these issues.

Signed-off-by: Jarkko Sakkinen <redacted>
Now this should work as Robertos patches move byte order conversion
where it should be. Sadly I'm out of reach to my Dell E6400 laptop
that I use for TPM 1.2 testing.
 drivers/char/tpm/tpm-interface.c | 30 ++++++++++++++++--------------
 drivers/char/tpm/tpm.h           | 13 -------------
 2 files changed, 16 insertions(+), 27 deletions(-)
I've now tested this with TPM 1.2. Any complains?
Seems reasonable, but which linke had the problematic arithmetic?

Jason
Arithmetic should work but it's not a good practice to do additions,
substractions or multiplications in any other byte order than the CPU
byte order.

sparse also complains about this.
Can I get your Reviewed-by for this one?

/Jarkko
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