The bug is here: cstate = to_dpu_crtc_state(drm_crtc->state);
For the drm_for_each_crtc(), just like list_for_each_entry(), the list iterator 'drm_crtc' will point to a bogus position containing HEAD if the list is empty or no element is found. This case must be checked before any use of the iterator, otherwise it will lead to a invalid memory access.
To fix this bug, use a new variable 'iter' as the list iterator, while use the origin variable 'drm_crtc' as a dedicated pointer to point to the found element.
Cc: stable@vger.kernel.org Fixes: b107603b4ad0f ("drm/msm/dpu: map mixer/ctl hw blocks in encoder modeset") Signed-off-by: Xiaomeng Tong xiam0nd.tong@gmail.com --- drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c index 1e648db439f9..d3fdb18e96f9 100644 --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c @@ -965,7 +965,7 @@ static void dpu_encoder_virt_mode_set(struct drm_encoder *drm_enc, struct dpu_kms *dpu_kms; struct list_head *connector_list; struct drm_connector *conn = NULL, *conn_iter; - struct drm_crtc *drm_crtc; + struct drm_crtc *drm_crtc = NULL, *iter; struct dpu_crtc_state *cstate; struct dpu_global_state *global_state; struct dpu_hw_blk *hw_pp[MAX_CHANNELS_PER_ENC]; @@ -1007,9 +1007,14 @@ static void dpu_encoder_virt_mode_set(struct drm_encoder *drm_enc, return; }
- drm_for_each_crtc(drm_crtc, drm_enc->dev) - if (drm_crtc->state->encoder_mask & drm_encoder_mask(drm_enc)) + drm_for_each_crtc(iter, drm_enc->dev) + if (iter->state->encoder_mask & drm_encoder_mask(drm_enc)) { + drm_crtc = iter; break; + } + + if (!drm_crtc) + return;
/* Query resource that have been reserved in atomic check step. */ num_pp = dpu_rm_get_assigned_resources(&dpu_kms->rm, global_state,