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SubjectRe: drm/amd/display: Add HDCP module - static analysis bug report
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I misunderstood and was talking about the ksv validation specifically 
(usage of drm_hdcp_check_ksvs_revoked()).

For the defines I will create patches to use drm_hdcp where it is usable.


Bhawan

On 2019-10-09 2:43 p.m., Daniel Vetter wrote:
> On Wed, Oct 9, 2019 at 8:23 PM Lakha, Bhawanpreet
> <Bhawanpreet.Lakha@amd.com> wrote:
>> Hi,
>>
>> The reason we don't use drm_hdcp is because our policy is to do hdcp
>> verification using PSP/HW (onboard secure processor).
> i915 also uses hw to auth, we still use the parts from drm_hdcp ...
> Did you actually look at what's in there? It's essentially just shared
> defines and data structures from the standard, plus a few minimal
> helpers to en/decode some bits. Just from a quick read the entire
> patch very much looks like midlayer everywhere design that we
> discussed back when DC landed ...
> -Daniel
>
>> Bhawan
>>
>> On 2019-10-09 12:32 p.m., Daniel Vetter wrote:
>>> On Thu, Oct 03, 2019 at 11:08:03PM +0100, Colin Ian King wrote:
>>>> Hi,
>>>>
>>>> Static analysis with Coverity has detected a potential issue with
>>>> function validate_bksv in
>>>> drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c with recent
>>>> commit:
>>>>
>>>> commit ed9d8e2bcb003ec94658cafe9b1bb3960e2139ec
>>>> Author: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
>>>> Date: Tue Aug 6 17:52:01 2019 -0400
>>>>
>>>> drm/amd/display: Add HDCP module
>>> I think the real question here is ... why is this not using drm_hdcp?
>>> -Daniel
>>>
>>>> The analysis is as follows:
>>>>
>>>> 28 static inline enum mod_hdcp_status validate_bksv(struct mod_hdcp *hdcp)
>>>> 29 {
>>>>
>>>> CID 89852 (#1 of 1): Out-of-bounds read (OVERRUN)
>>>>
>>>> 1. overrun-local:
>>>> Overrunning array of 5 bytes at byte offset 7 by dereferencing pointer
>>>> (uint64_t *)hdcp->auth.msg.hdcp1.bksv.
>>>>
>>>> 30 uint64_t n = *(uint64_t *)hdcp->auth.msg.hdcp1.bksv;
>>>> 31 uint8_t count = 0;
>>>> 32
>>>> 33 while (n) {
>>>> 34 count++;
>>>> 35 n &= (n - 1);
>>>> 36 }
>>>>
>>>> hdcp->auth.msg.hdcp1.bksv is an array of 5 uint8_t as defined in
>>>> drivers/gpu/drm/amd/display/modules/hdcp/hdcp.h as follows:
>>>>
>>>> struct mod_hdcp_message_hdcp1 {
>>>> uint8_t an[8];
>>>> uint8_t aksv[5];
>>>> uint8_t ainfo;
>>>> uint8_t bksv[5];
>>>> uint16_t r0p;
>>>> uint8_t bcaps;
>>>> uint16_t bstatus;
>>>> uint8_t ksvlist[635];
>>>> uint16_t ksvlist_size;
>>>> uint8_t vp[20];
>>>>
>>>> uint16_t binfo_dp;
>>>> };
>>>>
>>>> variable n is going to contain the contains of r0p and bcaps. I'm not
>>>> sure if that is intentional. If not, then the count is going to be
>>>> incorrect if these are non-zero.
>>>>
>>>> Colin
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>
>
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