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From:   Drew Davenport <ddavenport@chromium.org>
To:     intel-gfx@lists.freedesktop.org
Cc:     Drew Davenport <ddavenport@chromium.org>,
        Daniel Vetter <daniel@ffwll.ch>,
        David Airlie <airlied@gmail.com>,
        Imre Deak <imre.deak@intel.com>,
        Jani Nikula <jani.nikula@linux.intel.com>,
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        <ville.syrjala@linux.intel.com>, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] drm/i915/display: Check source height is > 0
Date:   Mon, 26 Dec 2022 22:53:24 -0700
Message-Id: <20221226225246.1.I15dff7bb5a0e485c862eae61a69096caf12ef29f@changeid>
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The error message suggests that the height of the src rect must be at
least 1. Reject source with height of 0.

Signed-off-by: Drew Davenport <ddavenport@chromium.org>

---
I was investigating some divide-by-zero crash reports on ChromeOS which
pointed to the intel_adjusted_rate function. Further prodding showed
that I could reproduce this in a simple test program if I made src_h
some value less than 1 but greater than 0.

This seemed to be a sensible place to check that the source height is at
least 1. I tried to repro this issue on an amd device I had on hand, and
the configuration was rejected.

Would it make sense to add a check that source dimensions are at least 1
somewhere in core, like in drm_atomic_plane_check? Or is that a valid
use case on some devices, and thus any such check should be done on a
per-driver basis?

Thanks.

 drivers/gpu/drm/i915/display/skl_universal_plane.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/skl_universal_plane.c b/drivers/gpu/drm/i915/display/skl_universal_plane.c
index 4b79c2d2d6177..9b172a1e90deb 100644
--- a/drivers/gpu/drm/i915/display/skl_universal_plane.c
+++ b/drivers/gpu/drm/i915/display/skl_universal_plane.c
@@ -1627,7 +1627,7 @@ static int skl_check_main_surface(struct intel_plane_state *plane_state)
 	u32 offset;
 	int ret;
 
-	if (w > max_width || w < min_width || h > max_height) {
+	if (w > max_width || w < min_width || h > max_height || h < 1) {
 		drm_dbg_kms(&dev_priv->drm,
 			    "requested Y/RGB source size %dx%d outside limits (min: %dx1 max: %dx%d)\n",
 			    w, h, min_width, max_width, max_height);
-- 
2.39.0.314.g84b9a713c41-goog