Commit 898a9e3f authored May 15, 2023 by Raphael Gallais-Pou Committed by Philippe Cornu May 26, 2023

drm/stm: ltdc: fix late dereference check

In ltdc_crtc_set_crc_source(), struct drm_crtc was dereferenced in a
container_of() before the pointer check. This could cause a kernel panic.

Fix this smatch warning:
drivers/gpu/drm/stm/ltdc.c:1124 ltdc_crtc_set_crc_source() warn: variable dereferenced before check 'crtc' (see line 1119)

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/lkml/202212241802.zeLFZCXB-lkp@intel.com/

Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/lkml/202212241802.zeLFZCXB-lkp@intel.com/

Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>
Acked-by: Philippe Cornu <philippe.cornu@foss.st.com>
Signed-off-by: Philippe Cornu <philippe.cornu@foss.st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230515123818.93971-1-raphael.gallais-pou@foss.st.com

parent 34235f54

drivers/gpu/drm/stm/ltdc.c

+3 −1

Original line number	Diff line number	Diff line
		@@ -1145,7 +1145,7 @@ static void ltdc_crtc_disable_vblank(struct drm_crtc *crtc)

		static int ltdc_crtc_set_crc_source(struct drm_crtc crtc, const char source)
		{
		struct ltdc_device *ldev = crtc_to_ltdc(crtc);
		struct ltdc_device *ldev;
		int ret;

		DRM_DEBUG_DRIVER("\n");
		@@ -1153,6 +1153,8 @@ static int ltdc_crtc_set_crc_source(struct drm_crtc crtc, const char source)
		if (!crtc)
		return -ENODEV;

		ldev = crtc_to_ltdc(crtc);

		if (source && strcmp(source, "auto") == 0) {
		ldev->crc_active = true;
		ret = regmap_set_bits(ldev->regmap, LTDC_GCR, GCR_CRCEN);