Re: [PATCH] drm/amd/display: Fix off by one in hdmi_14_process_transaction()

[Alex Deucher <alexdeucher@gmail.com>]

Applied.  Thanks!

Alex

On Tue, Mar 2, 2021 at 2:26 PM Lakha, Bhawanpreet
<Bhawanpreet.Lakha@amd.com> wrote:
>
> [AMD Official Use Only - Internal Distribution Only]
>
>
> Thanks
>
> Reviewed-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
> ________________________________
> From: Dan Carpenter <dan.carpenter@oracle.com>
> Sent: March 2, 2021 6:15 AM
> To: Wentland, Harry <Harry.Wentland@amd.com>; Lakha, Bhawanpreet <Bhawanpreet.Lakha@amd.com>
> Cc: Li, Sun peng (Leo) <Sunpeng.Li@amd.com>; Deucher, Alexander <Alexander.Deucher@amd.com>; Koenig, Christian <Christian.Koenig@amd.com>; David Airlie <airlied@linux.ie>; Daniel Vetter <daniel@ffwll.ch>; Dan Carpenter <dan.carpenter@oracle.com>; Lakha, Bhawanpreet <Bhawanpreet.Lakha@amd.com>; Siqueira, Rodrigo <Rodrigo.Siqueira@amd.com>; Liu, Wenjing <Wenjing.Liu@amd.com>; amd-gfx@lists.freedesktop.org <amd-gfx@lists.freedesktop.org>; dri-devel@lists.freedesktop.org <dri-devel@lists.freedesktop.org>; kernel-janitors@vger.kernel.org <kernel-janitors@vger.kernel.org>
> Subject: [PATCH] drm/amd/display: Fix off by one in hdmi_14_process_transaction()
>
> The hdcp_i2c_offsets[] array did not have an entry for
> HDCP_MESSAGE_ID_WRITE_CONTENT_STREAM_TYPE so it led to an off by one
> read overflow.  I added an entry and copied the 0x0 value for the offset
> from similar code in drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c.
>
> I also declared several of these arrays as having HDCP_MESSAGE_ID_MAX
> entries.  This doesn't change the code, but it's just a belt and
> suspenders approach to try future proof the code.
>
> Fixes: 4c283fdac08a ("drm/amd/display: Add HDCP module")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> From static analysis, as mentioned in the commit message the offset
> is basically an educated guess.
>
> I reported this bug on Apr 16, 2020 but I guess we lost take of it.
>
>  drivers/gpu/drm/amd/display/dc/hdcp/hdcp_msg.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/dc/hdcp/hdcp_msg.c b/drivers/gpu/drm/amd/display/dc/hdcp/hdcp_msg.c
> index 5e384a8a83dc..51855a2624cf 100644
> --- a/drivers/gpu/drm/amd/display/dc/hdcp/hdcp_msg.c
> +++ b/drivers/gpu/drm/amd/display/dc/hdcp/hdcp_msg.c
> @@ -39,7 +39,7 @@
>  #define HDCP14_KSV_SIZE 5
>  #define HDCP14_MAX_KSV_FIFO_SIZE 127*HDCP14_KSV_SIZE
>
> -static const bool hdcp_cmd_is_read[] = {
> +static const bool hdcp_cmd_is_read[HDCP_MESSAGE_ID_MAX] = {
>          [HDCP_MESSAGE_ID_READ_BKSV] = true,
>          [HDCP_MESSAGE_ID_READ_RI_R0] = true,
>          [HDCP_MESSAGE_ID_READ_PJ] = true,
> @@ -75,7 +75,7 @@ static const bool hdcp_cmd_is_read[] = {
>          [HDCP_MESSAGE_ID_WRITE_CONTENT_STREAM_TYPE] = false
>  };
>
> -static const uint8_t hdcp_i2c_offsets[] = {
> +static const uint8_t hdcp_i2c_offsets[HDCP_MESSAGE_ID_MAX] = {
>          [HDCP_MESSAGE_ID_READ_BKSV] = 0x0,
>          [HDCP_MESSAGE_ID_READ_RI_R0] = 0x8,
>          [HDCP_MESSAGE_ID_READ_PJ] = 0xA,
> @@ -106,7 +106,8 @@ static const uint8_t hdcp_i2c_offsets[] = {
>          [HDCP_MESSAGE_ID_WRITE_REPEATER_AUTH_SEND_ACK] = 0x60,
>          [HDCP_MESSAGE_ID_WRITE_REPEATER_AUTH_STREAM_MANAGE] = 0x60,
>          [HDCP_MESSAGE_ID_READ_REPEATER_AUTH_STREAM_READY] = 0x80,
> -       [HDCP_MESSAGE_ID_READ_RXSTATUS] = 0x70
> +       [HDCP_MESSAGE_ID_READ_RXSTATUS] = 0x70,
> +       [HDCP_MESSAGE_ID_WRITE_CONTENT_STREAM_TYPE] = 0x0,
>  };
>
>  struct protection_properties {
> @@ -184,7 +185,7 @@ static const struct protection_properties hdmi_14_protection = {
>          .process_transaction = hdmi_14_process_transaction
>  };
>
> -static const uint32_t hdcp_dpcd_addrs[] = {
> +static const uint32_t hdcp_dpcd_addrs[HDCP_MESSAGE_ID_MAX] = {
>          [HDCP_MESSAGE_ID_READ_BKSV] = 0x68000,
>          [HDCP_MESSAGE_ID_READ_RI_R0] = 0x68005,
>          [HDCP_MESSAGE_ID_READ_PJ] = 0xFFFFFFFF,
> --
> 2.30.1
>
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