From: Damian Kos <dkos@xxxxxxxxxxx> [ Upstream commit fa68d4f8476bea4cdf441062b614b41bb85ef1da ] Some of the functions (like cdn_dp_dpcd_read, cdn_dp_get_edid_block) allow to read 64KiB, but the cdn_dp_mailbox_read_receive, that is used by them, can read only up to 255 bytes at once. Normally, it's not a big issue as DPCD or EDID reads won't (hopefully) exceed that value. The real issue here is the revocation list read during the HDCP authentication process. (problematic use case: https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-4.4/drivers/gpu/drm/rockchip/cdn-dp-reg.c#1152) The list can reach 127*5+4 bytes (num devs * 5 bytes per ID/Bksv + 4 bytes of an additional info). In other words - CTSes with HDCP Repeater won't pass without this fix. Oh, and the driver will most likely stop working (best case scenario). Signed-off-by: Damian Kos <dkos@xxxxxxxxxxx> Signed-off-by: Heiko Stuebner <heiko@xxxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/1541518625-25984-1-git-send-email-dkos@xxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/gpu/drm/rockchip/cdn-dp-reg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/rockchip/cdn-dp-reg.c b/drivers/gpu/drm/rockchip/cdn-dp-reg.c index b14d211f6c21..0ed7e91471f6 100644 --- a/drivers/gpu/drm/rockchip/cdn-dp-reg.c +++ b/drivers/gpu/drm/rockchip/cdn-dp-reg.c @@ -147,7 +147,7 @@ static int cdn_dp_mailbox_validate_receive(struct cdn_dp_device *dp, } static int cdn_dp_mailbox_read_receive(struct cdn_dp_device *dp, - u8 *buff, u8 buff_size) + u8 *buff, u16 buff_size) { u32 i; int ret; -- 2.19.1
