Commit 06888d57 authored by Kees Cook's avatar Kees Cook Committed by Alex Deucher

drm/amd/display: Avoid HDCP over-read and corruption

Instead of reading the desired 5 bytes of the actual target field,
the code was reading 8. This could result in a corrupted value if the
trailing 3 bytes were non-zero, so instead use an appropriately sized
and zero-initialized bounce buffer, and read only 5 bytes before casting
to u64.
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 66c46621
...@@ -29,8 +29,10 @@ static inline enum mod_hdcp_status validate_bksv(struct mod_hdcp *hdcp) ...@@ -29,8 +29,10 @@ static inline enum mod_hdcp_status validate_bksv(struct mod_hdcp *hdcp)
{ {
uint64_t n = 0; uint64_t n = 0;
uint8_t count = 0; uint8_t count = 0;
u8 bksv[sizeof(n)] = { };
memcpy(&n, hdcp->auth.msg.hdcp1.bksv, sizeof(uint64_t)); memcpy(bksv, hdcp->auth.msg.hdcp1.bksv, sizeof(hdcp->auth.msg.hdcp1.bksv));
n = *(uint64_t *)bksv;
while (n) { while (n) {
count++; count++;
......
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