linux-kernel - [PATCH 5.17 739/772] gma500: fix an incorrect NULL check on list iterator

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Date:   Tue,  7 Jun 2022 19:05:31 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Xiaomeng Tong <xiam0nd.tong@...il.com>,
        Patrik Jakobsson <patrik.r.jakobsson@...il.com>
Subject: [PATCH 5.17 739/772] gma500: fix an incorrect NULL check on list iterator

From: Xiaomeng Tong <xiam0nd.tong@...il.com>

commit bdef417d84536715145f6dc9cc3275c46f26295a upstream.

The bug is here:
	return crtc;

The list iterator value 'crtc' 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, return 'crtc' when found, otherwise return NULL.

Cc: stable@...r.kernel.org
fixes: 89c78134cc54d ("gma500: Add Poulsbo support")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@...il.com>
Signed-off-by: Patrik Jakobsson <patrik.r.jakobsson@...il.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220327052028.2013-1-xiam0nd.tong@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/gma500/psb_intel_display.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/gma500/psb_intel_display.c
+++ b/drivers/gpu/drm/gma500/psb_intel_display.c
@@ -535,14 +535,15 @@ void psb_intel_crtc_init(struct drm_devi
 
 struct drm_crtc *psb_intel_get_crtc_from_pipe(struct drm_device *dev, int pipe)
 {
-	struct drm_crtc *crtc = NULL;
+	struct drm_crtc *crtc;
 
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
 		struct gma_crtc *gma_crtc = to_gma_crtc(crtc);
+
 		if (gma_crtc->pipe == pipe)
-			break;
+			return crtc;
 	}
-	return crtc;
+	return NULL;
 }
 
 int gma_connector_clones(struct drm_device *dev, int type_mask)