linux-kernel - Re: [PATCH] ACPI/Processor: Fix failure of loading acpi-cpufreq driver

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Message-ID: <53608551.8010208@linux.intel.com>
Date:	Wed, 30 Apr 2014 13:08:33 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Lan Tianyu <tianyu.lan@...el.com>, rjw@...ysocki.net,
	lenb@...nel.org, katoh@...age.ne.jp, smf.linux@...world.com
CC:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ACPI/Processor: Fix failure of loading acpi-cpufreq driver

Hi Tianyu,
	With the suggested fix, we still need to protect
acpi_processor_hotadd_init() when pr->apic_id is -1,
otherwise it may cause invalid memory access.

Best Regards!
Gerry

diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
index c29c2c3ec0ad..e17befc54c34 100644
--- a/drivers/acpi/acpi_processor.c
+++ b/drivers/acpi/acpi_processor.c
@@ -170,6 +170,9 @@ static int acpi_processor_hotadd_init(struct
acpi_processor *pr)
        acpi_status status;
        int ret;

+       if (pr->apic_id < 0)
+               return -ENODEV;
+
        status = acpi_evaluate_integer(pr->handle, "_STA", NULL, &sta);
        if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_PRESENT))
                return -ENODEV;


On 2014/4/30 11:10, Lan Tianyu wrote:
> According commit d640113fe(ACPI: processor: fix acpi_get_cpuid for UP
> processor),  Bios may not provide _MAT or MADT tables and acpi_get_apicid()
> always returns -1. For these cases, original code will pass apic_id with
> vaule of -1 to acpi_map_cpuid() and it will check the acpi_id. If acpi_id
> is equal to zero, ignores apic_id and return zero for CPU0.
> 
> Commit b981513(ACPI / scan: bail out early if failed to parse APIC
> ID for CPU) changed the behavior. Return ENODEV when find apic_id is
> less than zero after calling acpi_get_apicid(). This causes acpi-cpufreq
> driver fails to be loaded on some machines. This patch is to fix it.
> 
> Reference:https://bugzilla.kernel.org/show_bug.cgi?id=73781
> Cc: stable@...r.kernel.org v3.14
> Reported-and-tested-by: KATO Hiroshi <katoh@...age.ne.jp>
> Reported-and-tested-by: Stuart Foster <smf.linux@...world.com>
> Signed-off-by: Lan Tianyu <tianyu.lan@...el.com>
> ---
>  drivers/acpi/acpi_processor.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/acpi/acpi_processor.c b/drivers/acpi/acpi_processor.c
> index c29c2c3..d55b603 100644
> --- a/drivers/acpi/acpi_processor.c
> +++ b/drivers/acpi/acpi_processor.c
> @@ -260,10 +260,8 @@ static int acpi_processor_get_info(struct acpi_device *device)
>  	}
>  
>  	apic_id = acpi_get_apicid(pr->handle, device_declaration, pr->acpi_id);
> -	if (apic_id < 0) {
> +	if (apic_id < 0)
>  		acpi_handle_debug(pr->handle, "failed to get CPU APIC ID.\n");
> -		return -ENODEV;
> -	}
>  	pr->apic_id = apic_id;
>  
>  	cpu_index = acpi_map_cpuid(pr->apic_id, pr->acpi_id);
> 
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