From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755481Ab2K3C0h (ORCPT ); Thu, 29 Nov 2012 21:26:37 -0500 Received: from intranet.asianux.com ([58.214.24.6]:61838 "EHLO intranet.asianux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753766Ab2K3C0g (ORCPT ); Thu, 29 Nov 2012 21:26:36 -0500 X-Spam-Score: -100.8 Message-ID: <50B8198D.5@asianux.com> Date: Fri, 30 Nov 2012 10:27:25 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: Alan Cox CC: "linux-kernel@vger.kernel.org" Subject: Re: [Suggestion] drivers/tty: drivers/char/: for MAX_ASYNC_BUFFER_SIZE References: <50B6E751.9000000@asianux.com> <50B6ED90.6060100@asianux.com> <20121129134136.36cbf936@pyramind.ukuu.org.uk> In-Reply-To: <20121129134136.36cbf936@pyramind.ukuu.org.uk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 于 2012年11月29日 21:41, Alan Cox 写道: > On Thu, 29 Nov 2012 13:07:28 +0800 > Chen Gang wrote: > >> Hello Greg Kroah-Hartman: >> >> for MAX_ASYNC_BUFFER_SIZE: >> it is defined as 4096; >> but for the max buffer size which it processes, is 65535. >> so suggest to #define MAX_ASYNC_BUFFER_SIZE 0x10000 (better than 0xffff) > > I don't see the need to change this. Possibly some of the old synclink > drivers need to check more carefully for overflows if configured for very > large frame sizes ? > I am just through code review (so it is only a suggestion), I will try to perform test. also welcome another members to help testing. this issue has effect with 4 synclink drivers (most of source code are the same). 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]; 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]; >> >> --------------------------------------------------------------------------------- >> Step 3: >> >> one sample in drivers/tty/n_gsm.c (same for another implementation) >> >> receive_buf is a function ptr which may be gsmld_receive_buf at line 2819. >> it does not check the length of count whether larger than MAX_ASYNC_BUFFER_SIZE. >> if count is larger than MAX_ASYNC_BUFFER_SIZE, will cause issue. > > Why should it - MAX_ASYNC_BUFFER_SIZE is an internal detail of the > synclink drivers. > > Alan > > no, not need. (excuse me, my English is not quite well, maybe you misunderstand what I said) at least, currently: the caller should be sure that the buffer length is enough (it seems not, I need test it). the internal has no duty to check it. -- Chen Gang Asianux Corporation