linux-kernel - [PATCH AUTOSEL 5.12 080/160] drm/amd/display: Fix crash during MPO + ODM combine mode recalculation

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Message-Id: <20210706111827.2060499-80-sashal@kernel.org>
Date:   Tue,  6 Jul 2021 07:17:06 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Aric Cyr <aric.cyr@....com>,
        Krunoslav Kovac <Krunoslav.Kovac@....com>,
        Stylon Wang <stylon.wang@....com>,
        Daniel Wheeler <daniel.wheeler@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.12 080/160] drm/amd/display: Fix crash during MPO + ODM combine mode recalculation

From: Aric Cyr <aric.cyr@....com>

[ Upstream commit 665f28507a2a3d8d72ed9afa9a2b9b17fd43add1 ]

[Why]
When calculating recout width for an MPO plane on a mode that's using
ODM combine, driver can calculate a negative value, resulting in a
crash.

[How]
For negative widths, use zero such that validation will prune the
configuration correctly and disallow MPO.

Signed-off-by: Aric Cyr <aric.cyr@....com>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@....com>
Acked-by: Stylon Wang <stylon.wang@....com>
Tested-by: Daniel Wheeler <daniel.wheeler@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/display/dc/core/dc_resource.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index 325e0d656d6a..749189eb20ba 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -733,6 +733,11 @@ static void calculate_recout(struct pipe_ctx *pipe_ctx)
 			if (split_idx == split_count) {
 				/* rightmost pipe is the remainder recout */
 				data->recout.width -= data->h_active * split_count - data->recout.x;
+
+				/* ODM combine cases with MPO we can get negative widths */
+				if (data->recout.width < 0)
+					data->recout.width = 0;
+
 				data->recout.x = 0;
 			} else
 				data->recout.width = data->h_active - data->recout.x;
-- 
2.30.2