| Message ID | 20220327061516.5076-1-xiam0nd.tong@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | tilcdc: tilcdc_external: fix an incorrect NULL check on list iterator | expand |
On 2022-03-27 9:15, Xiaomeng Tong wrote: > The bug is here: > if (!encoder) { > > The list iterator value 'encoder' will *always* be set and non-NULL > by list_for_each_entry(), so it is incorrect to assume that the > iterator value will be NULL if the list is empty or no element > is found. > > To fix the bug, use a new variable 'iter' as the list iterator, > while use the original variable 'encoder' as a dedicated pointer > to point to the found element. > > Cc: stable@vger.kernel.org > Fixes: ec9eab097a500 ("drm/tilcdc: Add drm bridge support for > attaching drm bridge drivers") > Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> Thanks for the patch. Good catch. Reviewed-by: Jyri Sarha <jyri.sarha@iki.fi> Tested-by: Jyri Sarha <jyri.sarha@iki.fi> I'll apply this to drm-misc-next in couple of days. Best regards, Jyri > --- > drivers/gpu/drm/tilcdc/tilcdc_external.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/tilcdc/tilcdc_external.c > b/drivers/gpu/drm/tilcdc/tilcdc_external.c > index 7594cf6e186e..3b86d002ef62 100644 > --- a/drivers/gpu/drm/tilcdc/tilcdc_external.c > +++ b/drivers/gpu/drm/tilcdc/tilcdc_external.c > @@ -60,11 +60,13 @@ struct drm_connector > *tilcdc_encoder_find_connector(struct drm_device *ddev, > int tilcdc_add_component_encoder(struct drm_device *ddev) > { > struct tilcdc_drm_private *priv = ddev->dev_private; > - struct drm_encoder *encoder; > + struct drm_encoder *encoder = NULL, *iter; > > - list_for_each_entry(encoder, &ddev->mode_config.encoder_list, head) > - if (encoder->possible_crtcs & (1 << priv->crtc->index)) > + list_for_each_entry(iter, &ddev->mode_config.encoder_list, head) > + if (iter->possible_crtcs & (1 << priv->crtc->index)) { > + encoder = iter; > break; > + } > > if (!encoder) { > dev_err(ddev->dev, "%s: No suitable encoder found\n", __func__);
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_external.c b/drivers/gpu/drm/tilcdc/tilcdc_external.c index 7594cf6e186e..3b86d002ef62 100644 --- a/drivers/gpu/drm/tilcdc/tilcdc_external.c +++ b/drivers/gpu/drm/tilcdc/tilcdc_external.c @@ -60,11 +60,13 @@ struct drm_connector *tilcdc_encoder_find_connector(struct drm_device *ddev, int tilcdc_add_component_encoder(struct drm_device *ddev) { struct tilcdc_drm_private *priv = ddev->dev_private; - struct drm_encoder *encoder; + struct drm_encoder *encoder = NULL, *iter; - list_for_each_entry(encoder, &ddev->mode_config.encoder_list, head) - if (encoder->possible_crtcs & (1 << priv->crtc->index)) + list_for_each_entry(iter, &ddev->mode_config.encoder_list, head) + if (iter->possible_crtcs & (1 << priv->crtc->index)) { + encoder = iter; break; + } if (!encoder) { dev_err(ddev->dev, "%s: No suitable encoder found\n", __func__);
The bug is here: if (!encoder) { The list iterator value 'encoder' will *always* be set and non-NULL by list_for_each_entry(), so it is incorrect to assume that the iterator value will be NULL if the list is empty or no element is found. To fix the bug, use a new variable 'iter' as the list iterator, while use the original variable 'encoder' as a dedicated pointer to point to the found element. Cc: stable@vger.kernel.org Fixes: ec9eab097a500 ("drm/tilcdc: Add drm bridge support for attaching drm bridge drivers") Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com> --- drivers/gpu/drm/tilcdc/tilcdc_external.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)