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stm: ltdc: fix two incorrect NULL checks on list iterator

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commit 2e6c86be0e upstream.

The two bugs are here:
	if (encoder) {
	if (bridge && bridge->timings)

The list iterator value 'encoder/bridge' will *always* be set and
non-NULL by drm_for_each_encoder()/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 old variable 'encoder/bridge' as a dedicated pointer
to point to the found element.

Cc: stable@vger.kernel.org
Fixes: 99e360442f ("drm/stm: Fix bus_flags handling")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
Acked-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220327055355.3808-1-xiam0nd.tong@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiaomeng Tong 2022-03-27 13:53:55 +08:00 committed by Greg Kroah-Hartman
parent 878f9c7a77
commit 8d37abe2c0
1 changed files with 10 additions and 6 deletions
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16
drivers/gpu/drm/stm/ltdc.c
View file

@ -528,8 +528,8 @@ static void ltdc_crtc_mode_set_nofb(struct drm_crtc *crtc)
struct drm_device *ddev = crtc->dev;
struct drm_connector_list_iter iter;
struct drm_connector *connector = NULL;
struct drm_encoder *encoder = NULL;
struct drm_bridge *bridge = NULL;
struct drm_encoder *encoder = NULL, *en_iter;
struct drm_bridge *bridge = NULL, *br_iter;
struct drm_display_mode *mode = &crtc->state->adjusted_mode;
u32 hsync, vsync, accum_hbp, accum_vbp, accum_act_w, accum_act_h;
u32 total_width, total_height;
@ -538,15 +538,19 @@ static void ltdc_crtc_mode_set_nofb(struct drm_crtc *crtc)
int ret;
/* get encoder from crtc */
drm_for_each_encoder(encoder, ddev)
if (encoder->crtc == crtc)
drm_for_each_encoder(en_iter, ddev)
if (en_iter->crtc == crtc) {
encoder = en_iter;
break;
}
if (encoder) {
/* get bridge from encoder */
list_for_each_entry(bridge, &encoder->bridge_chain, chain_node)
if (bridge->encoder == encoder)
list_for_each_entry(br_iter, &encoder->bridge_chain, chain_node)
if (br_iter->encoder == encoder) {
bridge = br_iter;
break;
}
/* Get the connector from encoder */
drm_connector_list_iter_begin(ddev, &iter);