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x86/apic: Fix signedness bug in APIC ID validity checks

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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
This commit is contained in:
Li RongQing
2018-04-10 09:16:06 +08:00
committed by Thomas Gleixner
parent d94a155c59
commit a774635db5
8 changed files with 16 additions and 13 deletions
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2
arch/x86/kernel/apic/x2apic_phys.c
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@@ -101,7 +101,7 @@ static int x2apic_phys_probe(void)
}
/* Common x2apic functions, also used by x2apic_cluster */
int x2apic_apic_id_valid(int apicid)
int x2apic_apic_id_valid(u32 apicid)
{
return 1;
}