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From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
To: Zhenyu Wang <zhenyuw@linux.intel.com>,
	Zhi Wang <zhi.a.wang@intel.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	David Airlie <airlied@linux.ie>
Cc: intel-gvt-dev@lists.freedesktop.org,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org,
	"Gustavo A. R. Silva" <gustavo@embeddedor.com>
Subject: [PATCH] drm/i915/gvt/scheduler: fix potential NULL pointer dereference
Date: Mon, 19 Mar 2018 14:30:53 -0500	[thread overview]
Message-ID: <20180319193053.GA7016@embeddedgus> (raw)

_workload_ is being dereferenced before it is null checked, hence
there is a potential null pointer dereference.

Fix this by moving the pointer dereference after _workload_ has
been null checked.

Addresses-Coverity-ID: 1430136 ("Dereference before null check")
Fixes: fa3dd623e559 ("drm/i915/gvt: keep oa config in shadow ctx")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/gpu/drm/i915/gvt/scheduler.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/scheduler.c b/drivers/gpu/drm/i915/gvt/scheduler.c
index 0681264..be1a297 100644
--- a/drivers/gpu/drm/i915/gvt/scheduler.c
+++ b/drivers/gpu/drm/i915/gvt/scheduler.c
@@ -60,9 +60,9 @@ static void set_context_pdp_root_pointer(
 static void sr_oa_regs(struct intel_vgpu_workload *workload,
 		u32 *reg_state, bool save)
 {
-	struct drm_i915_private *dev_priv = workload->vgpu->gvt->dev_priv;
-	u32 ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
-	u32 ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
+	struct drm_i915_private *dev_priv;
+	u32 ctx_oactxctrl;
+	u32 ctx_flexeu0;
 	int i = 0;
 	u32 flex_mmio[] = {
 		i915_mmio_reg_offset(EU_PERF_CNTL0),
@@ -77,6 +77,10 @@ static void sr_oa_regs(struct intel_vgpu_workload *workload,
 	if (!workload || !reg_state || workload->ring_id != RCS)
 		return;
 
+	dev_priv = workload->vgpu->gvt->dev_priv;
+	ctx_oactxctrl = dev_priv->perf.oa.ctx_oactxctrl_offset;
+	ctx_flexeu0 = dev_priv->perf.oa.ctx_flexeu0_offset;
+
 	if (save) {
 		workload->oactxctrl = reg_state[ctx_oactxctrl + 1];
 
-- 
2.7.4

             reply	other threads:[~2018-03-19 19:31 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-19 19:30 Gustavo A. R. Silva [this message]
2018-03-19 20:38 ` [PATCH] drm/i915/gvt/scheduler: fix potential NULL pointer dereference Chris Wilson
2018-03-19 20:50   ` Gustavo A. R. Silva
2018-03-19 21:23     ` Chris Wilson
2018-03-19 21:45       ` Gustavo A. R. Silva

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