linux-kernel - [PATCH] drm/fb: Fix pointer dereference before null check.

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Date:   Wed,  2 Aug 2017 13:00:13 -0500
From:   David Lechner <david@...hnology.com>
To:     dri-devel@...ts.freedesktop.org
Cc:     David Lechner <david@...hnology.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Sean Paul <seanpaul@...omium.org>,
        David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org
Subject: [PATCH] drm/fb: Fix pointer dereference before null check.

fb_crtc is used before a null check, so move the use after the null check.

This was just identified by inspection. I haven't actually observed a crash
here, so it is possible that the null check could be unnecessary.

Signed-off-by: David Lechner <david@...hnology.com>
---
 drivers/gpu/drm/drm_fb_helper.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index 2cc28f0..2d3f93e 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -2424,9 +2424,9 @@ static void drm_setup_crtcs(struct drm_fb_helper *fb_helper,
 		struct drm_display_mode *mode = modes[i];
 		struct drm_fb_helper_crtc *fb_crtc = crtcs[i];
 		struct drm_fb_offset *offset = &offsets[i];
-		struct drm_mode_set *modeset = &fb_crtc->mode_set;
 
 		if (mode && fb_crtc) {
+			struct drm_mode_set *modeset = &fb_crtc->mode_set;
 			struct drm_connector *connector =
 				fb_helper->connector_info[i]->connector;
 
-- 
2.7.4