From a3c286dcef7f8bc576a20f5d1e80624f6b4b93ee Mon Sep 17 00:00:00 2001 From: Thomas Zimmermann Date: Wed, 9 Feb 2022 17:16:13 +0100 Subject: [PATCH] drm/fb-helper: Fix clip rectangle height Computing the clip rectangle is prone to off-by-one errors when writes happen near the end of a memory page. Point the end of the memory area to the first trailing byte, so that (end - start) returns the area's length. Signed-off-by: Thomas Zimmermann Reviewed-by: Javier Martinez Canillas Link: https://patchwork.freedesktop.org/patch/msgid/20220209161617.3553-2-tzimmermann@suse.de --- 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 f15127a32f7a..a37fb4a980c8 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -699,7 +699,7 @@ void drm_fb_helper_deferred_io(struct fb_info *info, max = 0; list_for_each_entry(page, pagelist, lru) { start = page->index << PAGE_SHIFT; - end = start + PAGE_SIZE - 1; + end = start + PAGE_SIZE; min = min(min, start); max = max(max, end); }