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    Subject[PATCH 4.14 124/205] fbdev: fbmem: behave better with small rotated displays and many CPUs
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    [ Upstream commit f75df8d4b4fabfad7e3cba2debfad12741c6fde7 ]

    Blitting an image with "negative" offsets is not working since there
    is no clipping. It hopefully just crashes. For the bootup logo, there
    is protection so that blitting does not happen as the image is drawn
    further and further to the right (ROTATE_UR) or further and further
    down (ROTATE_CW). There is however no protection when drawing in the
    opposite directions (ROTATE_UD and ROTATE_CCW).

    Add back this protection.

    The regression is 20-odd years old but the mindless warning-killing
    mentality displayed in commit 34bdb666f4b2 ("fbdev: fbmem: remove
    positive test on unsigned values") is also to blame, methinks.

    Fixes: 448d479747b8 ("fbdev: fb_do_show_logo() updates")
    Signed-off-by: Peter Rosin <peda@axentia.se>
    Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
    Cc: Fabian Frederick <ffrederick@users.sourceforge.net>
    Cc: Geert Uytterhoeven <geert+renesas@glider.be>
    cc: Geoff Levand <geoff@infradead.org>
    Cc: James Simmons <jsimmons@users.sf.net>
    Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/video/fbdev/core/fbmem.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c
    index 11d73b5fc885..302cce7185e3 100644
    --- a/drivers/video/fbdev/core/fbmem.c
    +++ b/drivers/video/fbdev/core/fbmem.c
    @@ -435,7 +435,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
    image->dx += image->width + 8;
    }
    } else if (rotate == FB_ROTATE_UD) {
    - for (x = 0; x < num; x++) {
    + u32 dx = image->dx;
    +
    + for (x = 0; x < num && image->dx <= dx; x++) {
    info->fbops->fb_imageblit(info, image);
    image->dx -= image->width + 8;
    }
    @@ -447,7 +449,9 @@ static void fb_do_show_logo(struct fb_info *info, struct fb_image *image,
    image->dy += image->height + 8;
    }
    } else if (rotate == FB_ROTATE_CCW) {
    - for (x = 0; x < num; x++) {
    + u32 dy = image->dy;
    +
    + for (x = 0; x < num && image->dy <= dy; x++) {
    info->fbops->fb_imageblit(info, image);
    image->dy -= image->height + 8;
    }
    --
    2.19.1


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