From 1de770d23ed6a880928cda5d3292bbeeb8ae13e0 Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Wed, 26 Feb 2020 22:34:43 +0200
Subject: drm/i915: Fix bounds check in intel_get_shared_dpll_id()
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Git-commit: b48f4b3be9206b9f88bee16665eb785636a0cb38
Patch-mainline: v5.7-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

Fix an off-by-one error in the upper-bound check and while at it clear
up a bit the function.

Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226203455.23032-2-imre.deak@intel.com
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/i915/display/intel_dpll_mgr.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
index e5bfe5245276..6cf291754390 100644
--- a/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
+++ b/drivers/gpu/drm/i915/display/intel_dpll_mgr.c
@@ -103,11 +103,14 @@ enum intel_dpll_id
 intel_get_shared_dpll_id(struct drm_i915_private *dev_priv,
 			 struct intel_shared_dpll *pll)
 {
-	if (drm_WARN_ON(&dev_priv->drm, pll < dev_priv->shared_dplls ||
-			pll > &dev_priv->shared_dplls[dev_priv->num_shared_dpll]))
+	long pll_idx = pll - dev_priv->shared_dplls;
+
+	if (drm_WARN_ON(&dev_priv->drm,
+			pll_idx < 0 ||
+			pll_idx >= dev_priv->num_shared_dpll))
 		return -1;
 
-	return (enum intel_dpll_id) (pll - dev_priv->shared_dplls);
+	return pll_idx;
 }
 
 /* For ILK+ */
-- 
2.28.0