linux-kernel - [PATCH] drm/format-helper: Fix dst computation in drm_fb_xrgb8888_to_rgb888

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Date:   Wed, 17 Nov 2021 23:22:06 +0900
From:   Hector Martin <marcan@...can.st>
To:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Hector Martin <marcan@...can.st>, stable@...r.kernel.org
Subject: [PATCH] drm/format-helper: Fix dst computation in drm_fb_xrgb8888_to_rgb888_dstclip()

The dst pointer was being advanced by the clip width, not the full line
stride, resulting in corruption. The clip offset was also calculated
incorrectly.

Cc: stable@...r.kernel.org
Signed-off-by: Hector Martin <marcan@...can.st>
---
 drivers/gpu/drm/drm_format_helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index e676921422b8..12bc6b45e95b 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -366,12 +366,12 @@ void drm_fb_xrgb8888_to_rgb888_dstclip(void __iomem *dst, unsigned int dst_pitch
 		return;
 
 	vaddr += clip_offset(clip, fb->pitches[0], sizeof(u32));
-	dst += clip_offset(clip, dst_pitch, sizeof(u16));
+	dst += clip_offset(clip, dst_pitch, 3);
 	for (y = 0; y < lines; y++) {
 		drm_fb_xrgb8888_to_rgb888_line(dbuf, vaddr, linepixels);
 		memcpy_toio(dst, dbuf, dst_len);
 		vaddr += fb->pitches[0];
-		dst += dst_len;
+		dst += dst_pitch;
 	}
 
 	kfree(dbuf);
-- 
2.33.0