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ACPI: processor: Avoid NULL pointer dereferences at init time

PATCH In review Rafael J. Wysocki 2 participants 2 messages Oct 15, 2019 – Oct 16, 2019

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ACPI ACPI thermal driver
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Rafael J. Wysocki

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PATCH 1/1 ACPI: processor: Avoid NULL pointer dereferences at init time

rom: Rafael J. Wysocki <[email protected]>

If there are neither processor objects nor processor device objects in the ACPI tables, the per-CPU processors table will not be initialized and attempting to dereference pointers from there will cause the kernel to crash. This happens in acpi_processor_ppc_init() and acpi_thermal_cpufreq_init() after commit d15ce412737a ("ACPI:
cpufreq: Switch to QoS requests instead of cpufreq notifier") which didn't add the requisite NULL pointer checks in there.

Add the NULL pointer checks to acpi_processor_ppc_init() and acpi_thermal_cpufreq_init(), and to the corresponding "exit" routines.

While at it, drop redundant return instructions from acpi_processor_ppc_init() and acpi_thermal_cpufreq_init().

Fixes d15ce412737a ("ACPI: cpufreq: Switch to QoS requests instead of cpufreq notifier")
Reported-by Srinivas Pandruvada <[email protected]>
Signed-off-by Rafael J. Wysocki <[email protected]>
---
 drivers/acpi/processor_perflib.c |   10 ++++++----
 drivers/acpi/processor_thermal.c |   10 ++++++----
 2 files changed, 12 insertions(+), 8 deletions(-)
drivers/acpi/processor_perflib.c +6 -4
Index: linux-pm/drivers/acpi/processor_perflib.c
===================================================================
@@ -162,21 +162,23 @@ void acpi_processor_ppc_init(int cpu)
 	struct acpi_processor *pr = per_cpu(processors, cpu);
 	int ret;
 
+	if (!pr)
+		return;
+
 	ret = dev_pm_qos_add_request(get_cpu_device(cpu),
 				     &pr->perflib_req, DEV_PM_QOS_MAX_FREQUENCY,
 				     INT_MAX);
-	if (ret < 0) {
+	if (ret < 0)
 		pr_err("Failed to add freq constraint for CPU%d (%d)\n", cpu,
 		       ret);
-		return;
-	}
 }
 
 void acpi_processor_ppc_exit(int cpu)
 {
 	struct acpi_processor *pr = per_cpu(processors, cpu);
 
-	dev_pm_qos_remove_request(&pr->perflib_req);
+	if (pr)
+		dev_pm_qos_remove_request(&pr->perflib_req);
 }
 
 static int acpi_processor_get_performance_control(struct acpi_processor *pr)
drivers/acpi/processor_thermal.c +6 -4
Index: linux-pm/drivers/acpi/processor_thermal.c
===================================================================
@@ -130,21 +130,23 @@ void acpi_thermal_cpufreq_init(int cpu)
 	struct acpi_processor *pr = per_cpu(processors, cpu);
 	int ret;
 
+	if (!pr)
+		return;
+
 	ret = dev_pm_qos_add_request(get_cpu_device(cpu),
 				     &pr->thermal_req, DEV_PM_QOS_MAX_FREQUENCY,
 				     INT_MAX);
-	if (ret < 0) {
+	if (ret < 0)
 		pr_err("Failed to add freq constraint for CPU%d (%d)\n", cpu,
 		       ret);
-		return;
-	}
 }
 
 void acpi_thermal_cpufreq_exit(int cpu)
 {
 	struct acpi_processor *pr = per_cpu(processors, cpu);
 
-	dev_pm_qos_remove_request(&pr->thermal_req);
+	if (pr)
+		dev_pm_qos_remove_request(&pr->thermal_req);
 }
 #else				/* ! CONFIG_CPU_FREQ */
 static int cpufreq_get_max_state(unsigned int cpu)
Acked-by on v1 1/1
#1 lore raw
Quoted 17 lines · Rafael J. Wysocki

rom: Rafael J. Wysocki <[email protected]>

If there are neither processor objects nor processor device objects in the ACPI tables, the per-CPU processors table will not be initialized and attempting to dereference pointers from there will cause the kernel to crash. This happens in acpi_processor_ppc_init() and acpi_thermal_cpufreq_init() after commit d15ce412737a ("ACPI:
cpufreq: Switch to QoS requests instead of cpufreq notifier") which didn't add the requisite NULL pointer checks in there.

Add the NULL pointer checks to acpi_processor_ppc_init() and acpi_thermal_cpufreq_init(), and to the corresponding "exit" routines.

While at it, drop redundant return instructions from acpi_processor_ppc_init() and acpi_thermal_cpufreq_init().

Quoted 7 lines
Fixes d15ce412737a ("ACPI: cpufreq: Switch to QoS requests instead of cpufreq notifier")
Reported-by Srinivas Pandruvada <[email protected]>
Signed-off-by Rafael J. Wysocki <[email protected]>
---
 drivers/acpi/processor_perflib.c |   10 ++++++----
 drivers/acpi/processor_thermal.c |   10 ++++++----
 2 files changed, 12 insertions(+), 8 deletions(-)
Acked-by Viresh Kumar <[email protected]>
Signature · 1 line
viresh