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@xxxxxxxxxxxxxxx
Fixes: ec9eab097a500 ("drm/tilcdc: Add drm bridge support for
attaching drm bridge drivers")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@xxxxxxxxx>
Thanks for the patch. Good catch.
Reviewed-by: Jyri Sarha <jyri.sarha@xxxxxx>
Tested-by: Jyri Sarha <jyri.sarha@xxxxxx>
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__);
