From: Xiaomeng Tong xiam0nd.tong@gmail.com
commit 8b917cbe38e9b0d002492477a9fc2bfee2412ce4 upstream.
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 Reviewed-by: Jyri Sarha jyri.sarha@iki.fi Tested-by: Jyri Sarha jyri.sarha@iki.fi Signed-off-by: Jyri Sarha jyri.sarha@iki.fi Link: https://patchwork.freedesktop.org/patch/msgid/20220327061516.5076-1-xiam0nd.... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/tilcdc/tilcdc_external.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/tilcdc/tilcdc_external.c +++ b/drivers/gpu/drm/tilcdc/tilcdc_external.c @@ -58,11 +58,13 @@ struct drm_connector *tilcdc_encoder_fin 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__);