linux-kernel - [PATCH 1/6] powercap: intel_rapl: Fix a NULL pointer dereference bug

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Message-Id: <20240131113713.74779-2-rui.zhang@intel.com>
Date: Wed, 31 Jan 2024 19:37:08 +0800
From: Zhang Rui <rui.zhang@...el.com>
To: rafael.j.wysocki@...el.com
Cc: linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org
Subject: [PATCH 1/6] powercap: intel_rapl: Fix a NULL pointer dereference bug

A NULL pointer dereference bug is triggered when probing MMIO RAPL
driver on platforms with CPU ID not listed in intel_rapl_common CPU
model list.

This is because the intel_rapl_common module still probes on such
platforms even if 'defaults_msr' is not set after commit 1488ac990ac8
("powercap: intel_rapl: Allow probing without CPUID match"). Thus the
MMIO RAPL rp->priv->defaults is NULL when registering to RAPL framework.

Fix the problem by adding sanity check to ensure rp->priv->rapl_defaults
is always valid.

Fixes: 1488ac990ac8 ("powercap: intel_rapl: Allow probing without CPUID match")
Signed-off-by: Zhang Rui <rui.zhang@...el.com>
Cc: <stable@...r.kernel.org>
---
 drivers/powercap/intel_rapl_common.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/powercap/intel_rapl_common.c b/drivers/powercap/intel_rapl_common.c
index 2feed036c1cd..1a739afd47d9 100644
--- a/drivers/powercap/intel_rapl_common.c
+++ b/drivers/powercap/intel_rapl_common.c
@@ -759,6 +759,11 @@ static int rapl_config(struct rapl_package *rp)
 	default:
 		return -EINVAL;
 	}
+
+	/* defaults_msr can be NULL on unsupported platforms */
+	if (!rp->priv->defaults || !rp->priv->rpi)
+		return -ENODEV;
+
 	return 0;
 }

-- 
2.34.1