Re: [PATCH] drm/msm: don't tear down KMS twice when KMS init fails

[Konrad Dybcio]

On 7/23/26 11:52 AM, Dmitry Baryshkov wrote:
> When priv->kms_init() (mdp4_kms_init() / mdp5_kms_init()) fails partway
> through, both display drivers already tear their KMS state down via
> mdp4_destroy() / mdp5_kms_destroy() before returning the error. The
> common error path in msm_drm_init() then runs msm_drm_uninit() ->
> msm_drm_kms_uninit(), which tries to destroy the very same KMS a second
> time, which causes a use-after-free crash.
> 
> Bring MDP4/MDP5 in line with the DPU driver whose dpu_kms_init() doesn't
> perform error cleanup on the failure. Let the common path own the
> cleanup, instead of freeing the KMS from their error paths.
> 
> The crash trace for the reference:
> 
>   __lock_acquire from lock_acquire (kernel/locking/lockdep.c:5906 kernel/locking/lockdep.c:5863)
>   lock_acquire from touch_wq_lockdep_map (kernel/workqueue.c:4094 (discriminator 1))
>   touch_wq_lockdep_map from __flush_workqueue (kernel/workqueue.c:4136)
>   __flush_workqueue from msm_drm_kms_uninit (drivers/gpu/drm/msm/msm_kms.c:243 (discriminator 33))
>   msm_drm_kms_uninit from msm_drm_uninit (drivers/gpu/drm/msm/msm_drv.c:93)
>   msm_drm_uninit from msm_drm_init (drivers/gpu/drm/msm/msm_drv.c:184)
>   msm_drm_init from try_to_bring_up_aggregate_device (drivers/base/component.c:249 drivers/base/component.c:227)
>   try_to_bring_up_aggregate_device from __component_add (drivers/base/component.c:269 drivers/base/component.c:748)
>   __component_add from dsi_host_attach (drivers/gpu/drm/msm/dsi/dsi_host.c:1739)
>   dsi_host_attach from mipi_dsi_attach (drivers/gpu/drm/drm_mipi_dsi.c:383)
>   mipi_dsi_attach from sharp_nt_panel_probe (drivers/gpu/drm/panel/panel-sharp-ls043t1le01.c:247)
> 
> Fixes: 506efcba3129 ("drm/msm: carve out KMS code from msm_drv.c")
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>
> ---

Reviewed-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>

Konrad