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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
Download Patch File Download Diff File Expand all files Collapse all files

13
arch/x86/kernel/acpi/boot.c
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@@ -200,7 +200,7 @@ acpi_parse_x2apic(struct acpi_subtable_header *header, const unsigned long end)
{
struct acpi_madt_local_x2apic *processor = NULL;
#ifdef CONFIG_X86_X2APIC
int apic_id;
u32 apic_id;
u8 enabled;
#endif
@@ -222,10 +222,13 @@ acpi_parse_x2apic(struct acpi_subtable_header *header, const unsigned long end)
* to not preallocating memory for all NR_CPUS
* when we use CPU hotplug.
*/
if (!apic->apic_id_valid(apic_id) && enabled)
printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
else
acpi_register_lapic(apic_id, processor->uid, enabled);
if (!apic->apic_id_valid(apic_id)) {
if (enabled)
pr_warn(PREFIX "x2apic entry ignored\n");
return 0;
}
acpi_register_lapic(apic_id, processor->uid, enabled);
#else
printk(KERN_WARNING PREFIX "x2apic entry ignored\n");
#endif