On Mon, 2017-06-26 at 10:18 +0200, Maarten Lankhorst wrote:
> When reading all debugfs files on a system with DP-MST the kernel panics
> on a null pointer dereference because intel_dp is null for a DP-MST
> connector. Detect this case and skip those connectors.
>
> Also fix the write for the DP compliance file in the same way.
>
> Changes since v1:
> - Fix i915_displayport_test_active_write too. (DK)
>
Avoids NULL pointer dereferences in all instances of enc_to_intel_dp()
inside compliance related functions, so
Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
This is the second instance where enc_to_intel_dp(mst_encoder) has
caused kernel panics. I wonder if we should change enc_to_intel_dp() to
check for encoder type.
-DK
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
> Cc: Manasi Navare <manasi.d.navare@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 44 +++++++++++++++++++++++++++----------
> 1 file changed, 32 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index f7aa6cbe3a2e..76b07a9b3548 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -3778,13 +3778,18 @@ static ssize_t i915_displayport_test_active_write(struct file *file,
>
> drm_connector_list_iter_begin(dev, &conn_iter);
> drm_for_each_connector_iter(connector, &conn_iter) {
> + struct intel_encoder *encoder;
> +
> if (connector->connector_type !=
> DRM_MODE_CONNECTOR_DisplayPort)
> continue;
>
> - if (connector->status == connector_status_connected &&
> - connector->encoder != NULL) {
> - intel_dp = enc_to_intel_dp(connector->encoder);
> + encoder = to_intel_encoder(connector->encoder);
> + if (encoder && encoder->type == INTEL_OUTPUT_DP_MST)
> + continue;
> +
> + if (encoder && connector->status == connector_status_connected) {
> + intel_dp = enc_to_intel_dp(&encoder->base);
> status = kstrtoint(input_buffer, 10, &val);
> if (status < 0)
> break;
> @@ -3816,13 +3821,18 @@ static int i915_displayport_test_active_show(struct seq_file *m, void *data)
>
> drm_connector_list_iter_begin(dev, &conn_iter);
> drm_for_each_connector_iter(connector, &conn_iter) {
> + struct intel_encoder *encoder;
> +
> if (connector->connector_type !=
> DRM_MODE_CONNECTOR_DisplayPort)
> continue;
>
> - if (connector->status == connector_status_connected &&
> - connector->encoder != NULL) {
> - intel_dp = enc_to_intel_dp(connector->encoder);
> + encoder = to_intel_encoder(connector->encoder);
> + if (encoder && encoder->type == INTEL_OUTPUT_DP_MST)
> + continue;
> +
> + if (encoder && connector->status == connector_status_connected) {
> + intel_dp = enc_to_intel_dp(&encoder->base);
> if (intel_dp->compliance.test_active)
> seq_puts(m, "1");
> else
> @@ -3862,13 +3872,18 @@ static int i915_displayport_test_data_show(struct seq_file *m, void *data)
>
> drm_connector_list_iter_begin(dev, &conn_iter);
> drm_for_each_connector_iter(connector, &conn_iter) {
> + struct intel_encoder *encoder;
> +
> if (connector->connector_type !=
> DRM_MODE_CONNECTOR_DisplayPort)
> continue;
>
> - if (connector->status == connector_status_connected &&
> - connector->encoder != NULL) {
> - intel_dp = enc_to_intel_dp(connector->encoder);
> + encoder = to_intel_encoder(connector->encoder);
> + if (encoder && encoder->type == INTEL_OUTPUT_DP_MST)
> + continue;
> +
> + if (encoder && connector->status == connector_status_connected) {
> + intel_dp = enc_to_intel_dp(&encoder->base);
> if (intel_dp->compliance.test_type ==
> DP_TEST_LINK_EDID_READ)
> seq_printf(m, "%lx",
> @@ -3915,13 +3930,18 @@ static int i915_displayport_test_type_show(struct seq_file *m, void *data)
>
> drm_connector_list_iter_begin(dev, &conn_iter);
> drm_for_each_connector_iter(connector, &conn_iter) {
> + struct intel_encoder *encoder;
> +
> if (connector->connector_type !=
> DRM_MODE_CONNECTOR_DisplayPort)
> continue;
>
> - if (connector->status == connector_status_connected &&
> - connector->encoder != NULL) {
> - intel_dp = enc_to_intel_dp(connector->encoder);
> + encoder = to_intel_encoder(connector->encoder);
> + if (encoder && encoder->type == INTEL_OUTPUT_DP_MST)
> + continue;
> +
> + if (encoder && connector->status == connector_status_connected) {
> + intel_dp = enc_to_intel_dp(&encoder->base);
> seq_printf(m, "%02lx", intel_dp->compliance.test_type);
> } else
> seq_puts(m, "0");
_______________________________________________
Intel-gfx mailing list
Intel-gfx@xxxxxxxxxxxxxxxxxxxxx
https://lists.freedesktop.org/mailman/listinfo/intel-gfx
