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

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

drivers/gpu/drm/amd/display/modules/hdcp/hdcp1_execution.c

+3 −1
Original line number Diff line number Diff line
@@ -29,8 +29,10 @@ static inline enum mod_hdcp_status validate_bksv(struct mod_hdcp *hdcp) 
{

	uint64_t n = 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) {

		count++;