• Li RongQing's avatar
    x86/apic: Fix signedness bug in APIC ID validity checks · a774635d
    Li RongQing authored
    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: default avatarLi RongQing <lirongqing@baidu.com>
    Signed-off-by: default avatarThomas 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
    a774635d
x2apic_uv_x.c 41.2 KB