Commit a62591e3 authored Mar 27, 2022 by Xiaomeng Tong Committed by Greg Kroah-Hartman Jun 14, 2022

tilcdc: tilcdc_external: fix an incorrect NULL check on list iterator



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: ec9eab09 ("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.tong@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 77ec584d

drivers/gpu/drm/tilcdc/tilcdc_external.c

+5 −3

Original line number	Diff line number	Diff line
		@@ -58,11 +58,13 @@ 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__);