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linux-next/arch/x86/kernel/apic/apic_common.c
Li RongQing a774635db5 x86/apic: Fix signedness bug in APIC ID validity checks
The APIC ID as parsed from ACPI MADT is validity checked with the
apic->apic_id_valid() callback, which depends on the selected APIC type.

For non X2APIC types APIC IDs >= 0xFF are invalid, but values > 0x7FFFFFFF
are detected as valid. This happens because the 'apicid' argument of the
apic_id_valid() callback is type 'int'. So the resulting comparison

   apicid < 0xFF

evaluates to true for all unsigned int values > 0x7FFFFFFF which are handed
to default_apic_id_valid(). As a consequence, invalid APIC IDs in !X2APIC
mode are considered valid and accounted as possible CPUs.

Change the apicid argument type of the apic_id_valid() callback to u32 so
the evaluation is unsigned and returns the correct result.

[ tglx: Massaged changelog ]

Signed-off-by: Li RongQing <lirongqing@baidu.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Cc: jgross@suse.com
Cc: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/1523322966-10296-1-git-send-email-lirongqing@baidu.com
2018-04-10 16:46:39 +02:00

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C

/*
* Common functions shared between the various APIC flavours
*
* SPDX-License-Identifier: GPL-2.0
*/
#include <linux/irq.h>
#include <asm/apic.h>
u32 apic_default_calc_apicid(unsigned int cpu)
{
return per_cpu(x86_cpu_to_apicid, cpu);
}
u32 apic_flat_calc_apicid(unsigned int cpu)
{
return 1U << cpu;
}
bool default_check_apicid_used(physid_mask_t *map, int apicid)
{
return physid_isset(apicid, *map);
}
void default_ioapic_phys_id_map(physid_mask_t *phys_map, physid_mask_t *retmap)
{
*retmap = *phys_map;
}
int default_cpu_present_to_apicid(int mps_cpu)
{
if (mps_cpu < nr_cpu_ids && cpu_present(mps_cpu))
return (int)per_cpu(x86_bios_cpu_apicid, mps_cpu);
else
return BAD_APICID;
}
EXPORT_SYMBOL_GPL(default_cpu_present_to_apicid);
int default_check_phys_apicid_present(int phys_apicid)
{
return physid_isset(phys_apicid, phys_cpu_present_map);
}
int default_apic_id_valid(u32 apicid)
{
return (apicid < 255);
}