linux-kernel - [PATCH 4.14 61/69] drm/i915/overlay: Prevent divide by zero bugs in scaling

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Message-Id: <20220207103757.629393379@linuxfoundation.org>
Date:   Mon,  7 Feb 2022 12:06:23 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Ville Syrjälä 
        <ville.syrjala@...ux.intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Subject: [PATCH 4.14 61/69] drm/i915/overlay: Prevent divide by zero bugs in scaling

From: Dan Carpenter <dan.carpenter@...cle.com>

commit 90a3d22ff02b196d5884e111f39271a1d4ee8e3e upstream.

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@...cle.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220124122409.GA31673@kili
(cherry picked from commit cf5b64f7f10b28bebb9b7c9d25e7aee5cbe43918)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/gpu/drm/i915/intel_overlay.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/gpu/drm/i915/intel_overlay.c
+++ b/drivers/gpu/drm/i915/intel_overlay.c
@@ -965,6 +965,9 @@ static int check_overlay_dst(struct inte
 	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 &&