FAILED: patch "[PATCH] drm/i915/overlay: Prevent divide by zero bugs in scaling" failed to apply to 4.9-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 90a3d22ff02b196d5884e111f39271a1d4ee8e3e Mon Sep 17 00:00:00 2001
From: Dan Carpenter <dan.carpenter@oracle.com>
Date: Mon, 24 Jan 2022 15:24:09 +0300
Subject: [PATCH] drm/i915/overlay: Prevent divide by zero bugs in scaling
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Smatch detected a divide by zero bug in check_overlay_scaling().

    drivers/gpu/drm/i915/display/intel_overlay.c:976 check_overlay_scaling()
    error: potential divide by zero bug '/ rec->dst_height'.
    drivers/gpu/drm/i915/display/intel_overlay.c:980 check_overlay_scaling()
    error: potential divide by zero bug '/ rec->dst_width'.

Prevent this by ensuring that the dst height and width are non-zero.

Fixes: 02e792fbaadb ("drm/i915: implement drmmode overlay support v4")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220124122409.GA31673@kili
(cherry picked from commit cf5b64f7f10b28bebb9b7c9d25e7aee5cbe43918)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c b/drivers/gpu/drm/i915/display/intel_overlay.c
index 1a376e9a1ff3..d610e48cab94 100644
--- a/drivers/gpu/drm/i915/display/intel_overlay.c
+++ b/drivers/gpu/drm/i915/display/intel_overlay.c
@@ -959,6 +959,9 @@ static int check_overlay_dst(struct intel_overlay *overlay,
 	const struct intel_crtc_state *pipe_config =
 		overlay->crtc->config;
 
+	if (rec->dst_height == 0 || rec->dst_width == 0)
+		return -EINVAL;
+
 	if (rec->dst_x < pipe_config->pipe_src_w &&
 	    rec->dst_x + rec->dst_width <= pipe_config->pipe_src_w &&
 	    rec->dst_y < pipe_config->pipe_src_h &&