| Message ID | 1640805422-21904-1-git-send-email-quic_khsieh@quicinc.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v2] drm/msm/dp: populate connector of struct dp_panel | expand |
Quoting Kuogee Hsieh (2021-12-29 11:17:02) > There is kernel crashed due to unable to handle kernel NULL > pointer dereference of dp_panel->connector while running DP link > layer compliance test case 4.2.2.6 (EDID Corruption Detection). Can you explain how we get into that situation? Like "We never assign struct dp_panel::connector, instead the connector is stored in struct msm_dp::connector. When we run compliance testing test case 4.2.2.6 dp_panel_handle_sink_request() won't have a valid edid set in struct dp_panel::edid so we'll try to use the connectors real_edid_checksum and hit a NULL pointer deref error because the connector pointer is never assigned." > This patch fixes this problem by populating connector of dp_panel. > > [drm:dp_panel_read_sink_caps] *ERROR* panel edid read failed > Unable to handle kernel NULL pointer dereference at virtual address 00000000000006e1 > Mem abort info: > ESR = 0x96000006 > EC = 0x25: DABT (current EL), IL = 32 bits > SET = 0, FnV = 0 > EA = 0, S1PTW = 0 > Data abort info: > ISV = 0, ISS = 0x00000006 > CM = 0, WnR = 0 > user pgtable: 4k pages, 39-bit VAs, pgdp=0000000115f25000 > [00000000000006e1] pgd=00000001174fe003, p4d=00000001174fe003, pud=00000001174fe003, pmd=0000000000000000 > Internal error: Oops: 96000006 [#1] PREEMPT SMP This sort of stuff isn't really useful because it takes quite a few lines to say "We hit a NULL pointer deref" which was already stated. I'd rather have a clear description of what goes wrong and how setting the pointer in msm_dp_modeset_init() fixes it. > {...] > > Changes in V2: > -- populate panel connector at msm_dp_modeset_init() instead of at dp_panel_read_sink_caps() > > Fixes: 7948fe12d47 ("drm/msm/dp: return correct edid checksum after corrupted edid checksum read") > Signee-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com> > --- > drivers/gpu/drm/msm/dp/dp_display.c | 25 +++++++++++++++---------- > 1 file changed, 15 insertions(+), 10 deletions(-) > > diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c > index 3449d3f..c282bbf 100644 > --- a/drivers/gpu/drm/msm/dp/dp_display.c > +++ b/drivers/gpu/drm/msm/dp/dp_display.c > @@ -1495,36 +1495,41 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor) > } > } > > -int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev, > +int msm_dp_modeset_init(struct msm_dp *dp, struct drm_device *dev, > struct drm_encoder *encoder) > { > struct msm_drm_private *priv; > + struct dp_display_private *dp_display; > int ret; > > - if (WARN_ON(!encoder) || WARN_ON(!dp_display) || WARN_ON(!dev)) > + if (WARN_ON(!encoder) || WARN_ON(!dp) || WARN_ON(!dev)) > return -EINVAL; > > priv = dev->dev_private; > - dp_display->drm_dev = dev; > + dp->drm_dev = dev; > + > + dp_display = container_of(dp, struct dp_display_private, dp_display); > > - ret = dp_display_request_irq(dp_display); > + ret = dp_display_request_irq(dp); > if (ret) { > DRM_ERROR("request_irq failed, ret=%d\n", ret); > return ret; > } > > - dp_display->encoder = encoder; > + dp->encoder = encoder; > > - dp_display->connector = dp_drm_connector_init(dp_display); > - if (IS_ERR(dp_display->connector)) { > - ret = PTR_ERR(dp_display->connector); > + dp->connector = dp_drm_connector_init(dp); > + if (IS_ERR(dp->connector)) { > + ret = PTR_ERR(dp->connector); > DRM_DEV_ERROR(dev->dev, > "failed to create dp connector: %d\n", ret); > - dp_display->connector = NULL; > + dp->connector = NULL; > return ret; > } > > - priv->connectors[priv->num_connectors++] = dp_display->connector; > + dp_display->panel->connector = dp->connector; This is the one line that matters I think? Can we reach the connector for the dp device without going through the panel in dp_panel_handle_sink_request()? That would reduce the number of struct elements if possible. > + > + priv->connectors[priv->num_connectors++] = dp->connector; Can we not rename all the local variables in this patch and do it later or never? Reading this patch takes a long time because we have to make sure nothing has actually changed with the rename of 'dp_display' to 'dp'. > return 0; > } > > -- > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, > a Linux Foundation Collaborative Project >
On 1/5/2022 1:34 PM, Stephen Boyd wrote: > Quoting Kuogee Hsieh (2021-12-29 11:17:02) >> There is kernel crashed due to unable to handle kernel NULL >> pointer dereference of dp_panel->connector while running DP link >> layer compliance test case 4.2.2.6 (EDID Corruption Detection). > Can you explain how we get into that situation? Like > > "We never assign struct dp_panel::connector, instead the connector is > stored in struct msm_dp::connector. When we run compliance testing test > case 4.2.2.6 dp_panel_handle_sink_request() won't have a valid edid set > in struct dp_panel::edid so we'll try to use the connectors > real_edid_checksum and hit a NULL pointer deref error because the > connector pointer is never assigned." > >> This patch fixes this problem by populating connector of dp_panel. >> >> [drm:dp_panel_read_sink_caps] *ERROR* panel edid read failed >> Unable to handle kernel NULL pointer dereference at virtual address 00000000000006e1 >> Mem abort info: >> ESR = 0x96000006 >> EC = 0x25: DABT (current EL), IL = 32 bits >> SET = 0, FnV = 0 >> EA = 0, S1PTW = 0 >> Data abort info: >> ISV = 0, ISS = 0x00000006 >> CM = 0, WnR = 0 >> user pgtable: 4k pages, 39-bit VAs, pgdp=0000000115f25000 >> [00000000000006e1] pgd=00000001174fe003, p4d=00000001174fe003, pud=00000001174fe003, pmd=0000000000000000 >> Internal error: Oops: 96000006 [#1] PREEMPT SMP > This sort of stuff isn't really useful because it takes quite a few > lines to say "We hit a NULL pointer deref" which was already stated. I'd > rather have a clear description of what goes wrong and how setting the > pointer in msm_dp_modeset_init() fixes it. > >> {...] >> >> Changes in V2: >> -- populate panel connector at msm_dp_modeset_init() instead of at dp_panel_read_sink_caps() >> >> Fixes: 7948fe12d47 ("drm/msm/dp: return correct edid checksum after corrupted edid checksum read") >> Signee-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com> >> --- >> drivers/gpu/drm/msm/dp/dp_display.c | 25 +++++++++++++++---------- >> 1 file changed, 15 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c >> index 3449d3f..c282bbf 100644 >> --- a/drivers/gpu/drm/msm/dp/dp_display.c >> +++ b/drivers/gpu/drm/msm/dp/dp_display.c >> @@ -1495,36 +1495,41 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor) >> } >> } >> >> -int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev, >> +int msm_dp_modeset_init(struct msm_dp *dp, struct drm_device *dev, >> struct drm_encoder *encoder) >> { >> struct msm_drm_private *priv; >> + struct dp_display_private *dp_display; >> int ret; >> >> - if (WARN_ON(!encoder) || WARN_ON(!dp_display) || WARN_ON(!dev)) >> + if (WARN_ON(!encoder) || WARN_ON(!dp) || WARN_ON(!dev)) >> return -EINVAL; >> >> priv = dev->dev_private; >> - dp_display->drm_dev = dev; >> + dp->drm_dev = dev; >> + >> + dp_display = container_of(dp, struct dp_display_private, dp_display); >> >> - ret = dp_display_request_irq(dp_display); >> + ret = dp_display_request_irq(dp); >> if (ret) { >> DRM_ERROR("request_irq failed, ret=%d\n", ret); >> return ret; >> } >> >> - dp_display->encoder = encoder; >> + dp->encoder = encoder; >> >> - dp_display->connector = dp_drm_connector_init(dp_display); >> - if (IS_ERR(dp_display->connector)) { >> - ret = PTR_ERR(dp_display->connector); >> + dp->connector = dp_drm_connector_init(dp); >> + if (IS_ERR(dp->connector)) { >> + ret = PTR_ERR(dp->connector); >> DRM_DEV_ERROR(dev->dev, >> "failed to create dp connector: %d\n", ret); >> - dp_display->connector = NULL; >> + dp->connector = NULL; >> return ret; >> } >> >> - priv->connectors[priv->num_connectors++] = dp_display->connector; >> + dp_display->panel->connector = dp->connector; > This is the one line that matters I think? Can we reach the connector > for the dp device without going through the panel in > dp_panel_handle_sink_request()? That would reduce the number of struct > elements if possible. I tried, but very difficulty. It will take more text section space. > >> + >> + priv->connectors[priv->num_connectors++] = dp->connector; > Can we not rename all the local variables in this patch and do it later > or never? Reading this patch takes a long time because we have to make > sure nothing has actually changed with the rename of 'dp_display' to > 'dp'. > >> return 0; >> } >> >> -- >> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, >> a Linux Foundation Collaborative Project >>
diff --git a/drivers/gpu/drm/msm/dp/dp_display.c b/drivers/gpu/drm/msm/dp/dp_display.c index 3449d3f..c282bbf 100644 --- a/drivers/gpu/drm/msm/dp/dp_display.c +++ b/drivers/gpu/drm/msm/dp/dp_display.c @@ -1495,36 +1495,41 @@ void msm_dp_debugfs_init(struct msm_dp *dp_display, struct drm_minor *minor) } } -int msm_dp_modeset_init(struct msm_dp *dp_display, struct drm_device *dev, +int msm_dp_modeset_init(struct msm_dp *dp, struct drm_device *dev, struct drm_encoder *encoder) { struct msm_drm_private *priv; + struct dp_display_private *dp_display; int ret; - if (WARN_ON(!encoder) || WARN_ON(!dp_display) || WARN_ON(!dev)) + if (WARN_ON(!encoder) || WARN_ON(!dp) || WARN_ON(!dev)) return -EINVAL; priv = dev->dev_private; - dp_display->drm_dev = dev; + dp->drm_dev = dev; + + dp_display = container_of(dp, struct dp_display_private, dp_display); - ret = dp_display_request_irq(dp_display); + ret = dp_display_request_irq(dp); if (ret) { DRM_ERROR("request_irq failed, ret=%d\n", ret); return ret; } - dp_display->encoder = encoder; + dp->encoder = encoder; - dp_display->connector = dp_drm_connector_init(dp_display); - if (IS_ERR(dp_display->connector)) { - ret = PTR_ERR(dp_display->connector); + dp->connector = dp_drm_connector_init(dp); + if (IS_ERR(dp->connector)) { + ret = PTR_ERR(dp->connector); DRM_DEV_ERROR(dev->dev, "failed to create dp connector: %d\n", ret); - dp_display->connector = NULL; + dp->connector = NULL; return ret; } - priv->connectors[priv->num_connectors++] = dp_display->connector; + dp_display->panel->connector = dp->connector; + + priv->connectors[priv->num_connectors++] = dp->connector; return 0; }
There is kernel crashed due to unable to handle kernel NULL pointer dereference of dp_panel->connector while running DP link layer compliance test case 4.2.2.6 (EDID Corruption Detection). This patch fixes this problem by populating connector of dp_panel. [drm:dp_panel_read_sink_caps] *ERROR* panel edid read failed Unable to handle kernel NULL pointer dereference at virtual address 00000000000006e1 Mem abort info: ESR = 0x96000006 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 Data abort info: ISV = 0, ISS = 0x00000006 CM = 0, WnR = 0 user pgtable: 4k pages, 39-bit VAs, pgdp=0000000115f25000 [00000000000006e1] pgd=00000001174fe003, p4d=00000001174fe003, pud=00000001174fe003, pmd=0000000000000000 Internal error: Oops: 96000006 [#1] PREEMPT SMP {...] Changes in V2: -- populate panel connector at msm_dp_modeset_init() instead of at dp_panel_read_sink_caps() Fixes: 7948fe12d47 ("drm/msm/dp: return correct edid checksum after corrupted edid checksum read") Signee-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com> --- drivers/gpu/drm/msm/dp/dp_display.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-)