Message-ID: <43ABAC48.20004@ccoss.com.cn>
Date: Fri, 23 Dec 2005 15:50:32 +0800
From: liyu <liyu@ccoss.com.cn>
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To: Al Viro <viro@ftp.linux.org.uk>
CC: linux-kernel@vger.kernel.org
Subject: Re: [WTF?] sys_tas() on m32r
References: <20051223061556.GR27946@ftp.linux.org.uk>
In-Reply-To: <20051223061556.GR27946@ftp.linux.org.uk>
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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


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