Uninitialized use of cmd.val in arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c:423

Uninitialized use of cmd.val in arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c:423

[Guillaume Chazarain]

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Hi,

In arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c:acpi_cpufreq_target()
cmd.val = (cmd.val & ~INTEL_MSR_RANGE) | msr;

cmd.val seems to be used uninitialized. So, one of the attached patch
should be needed. Both patches, and no patch at all, work for me though.

This is linux-2.6.20-rc3 and the code is really executed (I traced it) with
my Pentium M.

Thanks.

-- 
Guillaume


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diff -r 90710ed1291f arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
--- a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c	Mon Jan 01 01:00:04 2007 +0000
+++ b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c	Tue Jan 02 16:26:29 2007 +0100
@@ -372,7 +372,6 @@ static int acpi_cpufreq_target(struct cp
 	struct cpufreq_freqs freqs;
 	cpumask_t online_policy_cpus;
 	struct drv_cmd cmd;
-	unsigned int msr;
 	unsigned int next_state = 0;
 	unsigned int next_perf_state = 0;
 	unsigned int i;
@@ -417,10 +416,9 @@ static int acpi_cpufreq_target(struct cp
 	case SYSTEM_INTEL_MSR_CAPABLE:
 		cmd.type = SYSTEM_INTEL_MSR_CAPABLE;
 		cmd.addr.msr.reg = MSR_IA32_PERF_CTL;
-		msr =
+		cmd.val =
 		    (u32) perf->states[next_perf_state].
 		    control & INTEL_MSR_RANGE;
-		cmd.val = (cmd.val & ~INTEL_MSR_RANGE) | msr;
 		break;
 	case SYSTEM_IO_CAPABLE:
 		cmd.type = SYSTEM_IO_CAPABLE;

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diff -r 90710ed1291f arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
--- a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c	Mon Jan 01 01:00:04 2007 +0000
+++ b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c	Tue Jan 02 16:27:47 2007 +0100
@@ -420,6 +420,7 @@ static int acpi_cpufreq_target(struct cp
 		msr =
 		    (u32) perf->states[next_perf_state].
 		    control & INTEL_MSR_RANGE;
+		cmd.val = get_cur_val(online_policy_cpus);
 		cmd.val = (cmd.val & ~INTEL_MSR_RANGE) | msr;
 		break;
 	case SYSTEM_IO_CAPABLE:

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RE: Uninitialized use of cmd.val inarch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c:423

[Pallipadi, Venkatesh]

Thanks for the patch! This was indeed a bug in the driver..
Acking the second patch  acpi_cpufreq_uninitialized_cmd_val2 patch.

Can you please resend with description of the bug and Signed off line
and copy Dave so that he can pick up this patch.

Thanks,
Venki
 

>-----Original Message-----
>From: cpufreq-bounces@lists.linux.org.uk 
>[mailto:cpufreq-bounces@lists.linux.org.uk] On Behalf Of 
>Guillaume Chazarain
>Sent: Tuesday, January 02, 2007 7:49 AM
>To: cpufreq@lists.linux.org.uk
>Subject: Uninitialized use of cmd.val 
>inarch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c:423
>
>Hi,
>
>In arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c:acpi_cpufreq_target()
>cmd.val = (cmd.val & ~INTEL_MSR_RANGE) | msr;
>
>cmd.val seems to be used uninitialized. So, one of the attached patch
>should be needed. Both patches, and no patch at all, work for 
>me though.
>
>This is linux-2.6.20-rc3 and the code is really executed (I 
>traced it) with
>my Pentium M.
>
>Thanks.
>
>-- 
>Guillaume
>
>

[PATCH] Uninitialized use of cmd.val in arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c:acpi_cpufreq_target()

[Guillaume Chazarain]

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Fix for uninitialized use.

Thanks.

-- 
Guillaume


[-- Attachment #2: acpi-cpufreq-uninitialized-cmd_val.diff --]
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cmd.val was used uninitialized on the line below.

Signed-off-by: Guillaume Chazarain <guichaz@yahoo.fr>
Acked-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
---

diff -r 90710ed1291f arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
--- a/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c	Mon Jan 01 01:00:04 2007 +0000
+++ b/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c	Tue Jan 02 16:27:47 2007 +0100
@@ -420,6 +420,7 @@ static int acpi_cpufreq_target(struct cp
 		msr =
 		    (u32) perf->states[next_perf_state].
 		    control & INTEL_MSR_RANGE;
+		cmd.val = get_cur_val(online_policy_cpus);
 		cmd.val = (cmd.val & ~INTEL_MSR_RANGE) | msr;
 		break;
 	case SYSTEM_IO_CAPABLE:

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