linux-kernel - [PATCH 4.7 020/143] ACPI / CPPC: Prevent cpc_desc

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Date:   Mon,  5 Sep 2016 18:43:16 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hoan Tran <hotran@....com>,
        Ashwin Chaugule <ashwin.chaugule@...aro.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: [PATCH 4.7 020/143] ACPI / CPPC: Prevent cpc_desc_ptr points to the invalid data

4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hoan Tran <hotran@....com>

commit 2324d15447a9db168b1f85e3feac635b1ff8edb8 upstream.

When CPPC fails to request a PCC channel, the CPC data is freed
and cpc_desc_ptr points to the invalid data.

Avoid this issue by moving the cpc_desc_ptr assignment after the PCC
channel request.

Signed-off-by: Hoan Tran <hotran@....com>
Acked-by: Ashwin Chaugule <ashwin.chaugule@...aro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/acpi/cppc_acpi.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/acpi/cppc_acpi.c
+++ b/drivers/acpi/cppc_acpi.c
@@ -601,9 +601,6 @@ int acpi_cppc_processor_probe(struct acp
 	/* Store CPU Logical ID */
 	cpc_ptr->cpu_id = pr->id;
 
-	/* Plug it into this CPUs CPC descriptor. */
-	per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr;
-
 	/* Parse PSD data for this CPU */
 	ret = acpi_get_psd(cpc_ptr, handle);
 	if (ret)
@@ -616,6 +613,9 @@ int acpi_cppc_processor_probe(struct acp
 			goto out_free;
 	}
 
+	/* Plug PSD data into this CPUs CPC descriptor. */
+	per_cpu(cpc_desc_ptr, pr->id) = cpc_ptr;
+
 	/* Everything looks okay */
 	pr_debug("Parsed CPC struct for CPU: %d\n", pr->id);