| Message ID | 20220327073252.10871-1-xiam0nd.tong@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | dpu1: dpu_encoder: fix a missing check on list iterator | expand |
On 27/03/2022 10:32, Xiaomeng Tong wrote: > 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> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> > --- > 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,
On 11/04/2022 03:56, Dmitry Baryshkov wrote: > On 27/03/2022 10:32, Xiaomeng Tong wrote: >> 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> > > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> On the other hand, this code has been removed in 5.18-rc1 in the commit 764332bf96244cbc8baf08aa35844b29106da312. > >> --- >> 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, > >
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,
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(-)