On Tue, Jul 06, 2021 at 01:53:20PM -0700, Dave Hansen wrote:
On 7/5/21 7:36 AM, Jarkko Sakkinen wrote:
From: Tianjia Zhang tianjia.zhang@linux.alibaba.com
Q1 and Q2 are numbers with *maximum* length of 384 bytes. If the calculated length of Q1 and Q2 is less than 384 bytes, things will go wrong.
E.g. if Q2 is 383 bytes, then
- The bytes of q2 are copied to sigstruct->q2 in calc_q1q2().
- The entire sigstruct->q2 is reversed, which results it being 256 * Q2, given that the last byte of sigstruct->q2 is added to before the bytes given by calc_q1q2().
Either change in key or measurement can trigger the bug. E.g. an unmeasured heap could cause a devastating change in Q1 or Q2.
Reverse exactly the bytes of Q1 and Q2 in calc_q1q2() before returning to the caller.
Fixes: 2adcba79e69d ("selftests/x86: Add a selftest for SGX") Link: https://lore.kernel.org/linux-sgx/20210301051836.30738-1-tianjia.zhang@linux... Signed-off-by: Tianjia Zhang tianjia.zhang@linux.alibaba.com Signed-off-by: Jarkko Sakkinen jarkko@kernel.org
This looks fine, but can I suggest a Subject: tweak?
selftests/sgx: Fix calculations for sub-maximum field sizes
WFM
In any case:
Reviewed-by: Dave Hansen dave.hansen@linux.intel.com
Thank you.
/Jarkko