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SubjectRe: drm/amd/display: Add HDCP module - static analysis bug report
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

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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