Hi,
Static analysis on linux-next with Coverity has detected an issue in
drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c with the following commit:
commit c1c4d8efdddec8a0ccc8525b29740640bd652ce8
Author: Alex Deucher <alexander.deucher@xxxxxxx>
Date: Wed May 19 15:47:42 2021 -0400
drm/amdgpu/acpi: unify ATCS handling (v2)
The analysis is as follows:
805int amdgpu_acpi_init(struct amdgpu_device *adev)
806{
807 acpi_handle handle, atif_handle, atcs_handle;
808 struct amdgpu_atif *atif;
809 struct amdgpu_atcs *atcs;
1. var_decl: Declaring variable ret without initializer.
810 int ret;
811
812 /* Get the device handle */
2. Condition is_acpi_device_node(__to_acpi_device_node_fwnode),
taking true branch.
3. Condition 0 /* !!(!__builtin_types_compatible_p() &&
!__builtin_types_compatible_p()) */, taking false branch.
813 handle = ACPI_HANDLE(&adev->pdev->dev);
814
4. Condition !adev->bios, taking false branch.
5. Condition !handle, taking false branch.
815 if (!adev->bios || !handle)
816 return 0;
817
818 /* Probe for ATIF, and initialize it if found */
819 atif_handle = amdgpu_atif_probe_handle(handle);
6. Condition !atif_handle, taking true branch.
820 if (!atif_handle)
7. Jumping to label atcs.
821 goto atcs;
822
823 atif = kzalloc(sizeof(*atif), GFP_KERNEL);
824 if (!atif) {
825 DRM_WARN("Not enough memory to initialize ATIF\n");
826 goto atcs;
827 }
828 atif->handle = atif_handle;
829
830 /* Call the ATIF method */
831 ret = amdgpu_atif_verify_interface(atif);
832 if (ret) {
833 DRM_DEBUG_DRIVER("Call to ATIF verify_interface
failed: %d\n", ret);
834 kfree(atif);
835 goto atcs;
836 }
837 adev->atif = atif;
838
839#if defined(CONFIG_BACKLIGHT_CLASS_DEVICE) ||
defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)
840 if (atif->notifications.brightness_change) {
841 if (amdgpu_device_has_dc_support(adev)) {
842#if defined(CONFIG_DRM_AMD_DC)
843 struct amdgpu_display_manager *dm = &adev->dm;
844 if (dm->backlight_dev)
845 atif->bd = dm->backlight_dev;
846#endif
847 } else {
848 struct drm_encoder *tmp;
849
850 /* Find the encoder controlling the brightness */
851 list_for_each_entry(tmp,
&adev_to_drm(adev)->mode_config.encoder_list,
852 head) {
853 struct amdgpu_encoder *enc =
to_amdgpu_encoder(tmp);
854
855 if ((enc->devices &
(ATOM_DEVICE_LCD_SUPPORT)) &&
856 enc->enc_priv) {
857 struct
amdgpu_encoder_atom_dig *dig = enc->enc_priv;
858 if (dig->bl_dev) {
859 atif->bd = dig->bl_dev;
860 break;
861 }
862 }
863 }
864 }
865 }
866#endif
867
868 if (atif->functions.sbios_requests &&
!atif->functions.system_params) {
869 /* XXX check this workraround, if sbios request
function is
870 * present we have to see how it's configured in the
system
871 * params
872 */
873 atif->functions.system_params = true;
874 }
875
876 if (atif->functions.system_params) {
877 ret = amdgpu_atif_get_notification_params(atif);
878 if (ret) {
879 DRM_DEBUG_DRIVER("Call to GET_SYSTEM_PARAMS
failed: %d\n",
880 ret);
881 /* Disable notification */
882 atif->notification_cfg.enabled = false;
883 }
884 }
885
886 if (atif->functions.query_backlight_transfer_characteristics) {
887 ret = amdgpu_atif_query_backlight_caps(atif);
888 if (ret) {
889 DRM_DEBUG_DRIVER("Call to
QUERY_BACKLIGHT_TRANSFER_CHARACTERISTICS failed: %d\n",
890 ret);
891 atif->backlight_caps.caps_valid = false;
892 }
893 } else {
894 atif->backlight_caps.caps_valid = false;
895 }
896
897atcs:
898 /* Probe for ATCS, and initialize it if found */
899 atcs_handle = amdgpu_atcs_probe_handle(handle);
8. Condition !atcs_handle, taking true branch.
900 if (!atcs_handle)
9. Jumping to label out.
901 goto out;
902
903 atcs = kzalloc(sizeof(*atcs), GFP_KERNEL);
CID 114228: Uninitialized pointer read (UNINIT) [select issue]
904 if (!atif) {
905 DRM_WARN("Not enough memory to initialize ATCS\n");
906 goto out;
907 }
908 atcs->handle = atcs_handle;
909
910 /* Call the ATCS method */
911 ret = amdgpu_atcs_verify_interface(atcs);
912 if (ret) {
913 DRM_DEBUG_DRIVER("Call to ATCS verify_interface
failed: %d\n", ret);
914 kfree(atcs);
915 goto out;
916 }
917 adev->atcs = atcs;
918
919out:
920 adev->acpi_nb.notifier_call = amdgpu_acpi_event;
921 register_acpi_notifier(&adev->acpi_nb);
922
Uninitialized scalar variable (UNINIT)
10. uninit_use: Using uninitialized value ret.
923 return ret;
924}
The chain of gotos end up with an uninitialized ret being returned on an
error condition. I was sure what value to assign to ret for this error
case, so I'm reporting this issue.
Colin
