From: Chen Gang <gang.chen@asianux.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-serial@vger.kernel.org, Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [Suggestion] drivers/tty: drivers/char/: for MAX_ASYNC_BUFFER_SIZE
Date: Fri, 30 Nov 2012 10:52:38 +0800 [thread overview]
Message-ID: <50B81F76.8020508@asianux.com> (raw)
In-Reply-To: <20121129183207.GA4688@kroah.com>
于 2012年11月30日 02:32, Greg KH 写道:
> On Thu, Nov 29, 2012 at 01:57:59PM +0800, Chen Gang wrote:
>>> And, I really don't understand here, why do you want to change this?
>>> What is it going to change? And why?
>>>
>>
>> Why:
>> for the context MGSLPC_INFO *info in drivers/char/pcmcia/synclink_cs.c
>> info->max_frame_size can be the value between 4096 .. 65535 (can be
>> set by its module input parameter)
>> info->flag_buf length is 4096 (MAX_ASYNC_BUFFER_SIZE)
>> in function rx_get_frame
>> the framesize is limit by info->max_frame_size, but may still be
>> larger that 4096.
>> when call function ldisc_receive_buf, info->flag_buf is equal to
>> 4096, but framesize can be more than 4096. it will cause memory over flow.
>
> Do you use that pcmcia driver for anything? Are those cards still
> around?
I am not use them.
I am just through code review (so it is only a suggestion).
this issue has effect with 4 synclink drivers
I checked their source code, all of them have the same issue.
drivers/char/pcmcia/synclink_cs.c:213: char flag_buf[MAX_ASYNC_BUFFER_SIZE];
drivers/tty/synclink_gt.c:320: char flag_buf[MAX_ASYNC_BUFFER_SIZE];
drivers/tty/synclink.c:294: char flag_buf[MAX_ASYNC_BUFFER_SIZE];
drivers/tty/synclinkmp.c:265: char flag_buf[MAX_ASYNC_BUFFER_SIZE];
by the way, for the char_buf, has already useless (can be removed)
drivers/tty/synclink_gt.c:321: char char_buf[MAX_ASYNC_BUFFER_SIZE];
drivers/tty/synclink.c:295: char char_buf[MAX_ASYNC_BUFFER_SIZE];
drivers/tty/synclinkmp.c:266: char char_buf[MAX_ASYNC_BUFFER_SIZE];
>
>> What:
>> #define MAX_ASYNC_BUFFER_SIZE 0x10000 (instead of 4096, originally).
>> let it match the max frame size.
>>
>> At last:
>> my suggestion may be incorrect, need relative member (who expert about
>> it) to help checking.
>
> That driver might be incorrect, yes, care to make up a patch for it and
> test it to verify it fixes the problem?
>
and now Alan Cox has his own opinions
at least, I think it is valuable to continue discussing about it.
if Alan Cox agree with it (but it seems not), I will make patch, and try to perform test.
also welcome another members to help testing.
> thanks,
>
> greg k-h
>
>
--
Chen Gang
Asianux Corporation
next prev parent reply other threads:[~2012-11-30 2:51 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <50B6E751.9000000@asianux.com>
2012-11-29 5:07 ` [Suggestion] drivers/tty: drivers/char/: for MAX_ASYNC_BUFFER_SIZE Chen Gang
2012-11-29 13:41 ` Alan Cox
2012-11-30 2:27 ` Chen Gang
2012-11-30 3:39 ` Chen Gang
2012-11-29 5:13 ` 【Suggestion】drivers/tty: " Greg KH
2012-11-29 5:57 ` [Suggestion] drivers/tty: " Chen Gang
2012-11-29 6:14 ` [PATCH] MAINTAINERS: TTY - Add linux-serial mailing list Joe Perches
2012-11-29 6:27 ` Chen Gang
2012-11-29 8:23 ` Jiri Slaby
2012-11-29 18:32 ` [Suggestion] drivers/tty: drivers/char/: for MAX_ASYNC_BUFFER_SIZE Greg KH
2012-11-30 2:52 ` Chen Gang [this message]
[not found] ` <C7D3911F-7B6B-4353-A84B-0218FAB27198@microgate.com>
2012-11-30 6:28 ` Chen Gang
2012-11-30 7:14 ` Chen Gang
2012-11-30 16:24 ` Paul Fulghum
2012-11-30 19:46 ` [PATCH] synclink fix ldisc buffer argument Paul Fulghum
2012-12-02 15:13 ` Alan Cox
[not found] ` <F6B8A325-7DBF-4623-B16C-CDC5642EFD16@microgate.com>
2012-12-02 18:10 ` Alan Cox
[not found] ` <989CB961-79F8-479B-B16C-41358A60AC94@microgate.com>
2012-12-03 2:20 ` Chen Gang
2012-12-03 16:03 ` Paul Fulghum
2012-12-05 1:57 ` Chen Gang
2012-12-19 2:23 ` Chen Gang
2012-12-19 4:09 ` Greg KH
2012-12-19 4:10 ` Chen Gang
2012-12-20 4:16 ` [PATCH] drivers/tty/synclink: let receive buffer size match max frame size Chen Gang
2012-12-03 17:13 ` [PATCH] synclink fix ldisc buffer argument Paul Fulghum
2012-12-05 1:35 ` Chen Gang
2012-12-07 2:15 ` Chen Gang
2012-12-10 1:32 ` [Consult]: " Chen Gang
2012-12-01 9:01 ` [Suggestion] drivers/tty: drivers/char/: for MAX_ASYNC_BUFFER_SIZE Chen Gang
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