From 34d531e640cb805973cf656b15c716b961565cea Mon Sep 17 00:00:00 2001 From: Len Brown Date: Tue, 26 May 2009 15:11:06 -0400 Subject: [PATCH] ACPI: sanity check _PSS frequency to prevent cpufreq crash When BIOS SETUP is changed to disable EIST, some BIOS hand the OS an un-initialized _PSS: Name (_PSS, Package (0x06) { Package (0x06) { 0x80000000, // frequency [MHz] 0x80000000, // power [mW] 0x80000000, // latency [us] 0x80000000, // BM latency [us] 0x80000000, // control 0x80000000 // status }, ... These are outrageous values for frequency, power and latency, raising the question where to draw the line between legal and illegal. We tend to survive garbage in the power and latency fields, but we can BUG_ON when garbage is in the frequency field. Cpufreq multiplies the frequency by 1000 and stores it in a u32 KHz. So disregard a _PSS with a frequency so large that it can't be represented by cpufreq. https://bugzilla.redhat.com/show_bug.cgi?id=500311 Signed-off-by: Len Brown --- drivers/acpi/processor_perflib.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c index cafb41000f6b..60e543d3234e 100644 --- a/drivers/acpi/processor_perflib.c +++ b/drivers/acpi/processor_perflib.c @@ -309,9 +309,15 @@ static int acpi_processor_get_performance_states(struct acpi_processor *pr) (u32) px->bus_master_latency, (u32) px->control, (u32) px->status)); - if (!px->core_frequency) { - printk(KERN_ERR PREFIX - "Invalid _PSS data: freq is zero\n"); + /* + * Check that ACPI's u64 MHz will be valid as u32 KHz in cpufreq + */ + if (!px->core_frequency || + ((u32)(px->core_frequency * 1000) != + (px->core_frequency * 1000))) { + printk(KERN_ERR FW_BUG PREFIX + "Invalid BIOS _PSS frequency: 0x%llx MHz\n", + px->core_frequency); result = -EFAULT; kfree(pr->performance->states); goto end;