Re: [PATCH v2 2/2] tun: update file current position

Zhi Yong Wu
2013-12-06T20:32:23Z

On Sat, Dec 7, 2013 at 1:45 AM, David Miller <davem@davemloft.net> wrote:
> From: Zhi Yong Wu <zwu.kernel@gmail.com>
> Date: Fri, 6 Dec 2013 17:08:50 +0800
>
>> From: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
>>
>> Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
>
> Also applied and queued up for -stable, thanks.
>
> I noticed in these two cases that that min_t() adjustment of 'ret'
> seems strange. I can't understand why it's needed.
>
> If, for example, tun_do_read() really did read more than 'len'
> bytes:
>
> 1) That would write past the end of the buffer.
>
> 2) Writing a different value to the ->ki_pos would mean
> that ->ki_pos is now inaccurate.
>
> Unless someone can explain why the min_t() is needed, we should remove
> it.
Yes, from my side, it seems to be impossible that ret is bigger than
let or total_len.
So we also remove the branch "if (ret > total_len) {...}" in xxx_rcvmsg().
If you hope to submit the patch for this, please let me know, thanks.

--
Regards,

Zhi Yong Wu