Re: [WTF?] sys_tas() on m32r

[liyu <liyu@ccoss.com.cn>]

Al Viro 写道:

>asmlinkage int sys_tas(int *addr)
>{
>        int oldval;
>        unsigned long flags;
>
>        if (!access_ok(VERIFY_WRITE, addr, sizeof (int)))
>                return -EFAULT;
>        local_irq_save(flags);
>        oldval = *addr;
>        if (!oldval)
>                *addr = 1;
>        local_irq_restore(flags);
>        return oldval;
>}
>in arch/m32r/kernel/sys_m32r.c.  Trivial oops *AND* ability to trigger
>IO with interrupts disabled.
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The memory that parameter addr pointer is in user-space.
To access these memory, you should use function like copy_from_user().

-liyu