From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264705AbTFEOcj (ORCPT ); Thu, 5 Jun 2003 10:32:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264706AbTFEOcj (ORCPT ); Thu, 5 Jun 2003 10:32:39 -0400 Received: from air-2.osdl.org ([65.172.181.6]:61089 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S264705AbTFEOcg (ORCPT ); Thu, 5 Jun 2003 10:32:36 -0400 Subject: Re: [PATCH] megaraid driver fix for 2.5.70 From: Mark Haverkamp To: James Bottomley Cc: atulm@lsil.com, Linus Torvalds , Linux Kernel , linux-scsi In-Reply-To: <1054824142.1792.58.camel@mulgrave> References: <1054650567.13617.12.camel@markh1.pdx.osdl.net> <1054822044.1792.48.camel@mulgrave> <1054823593.13060.12.camel@markh1.pdx.osdl.net> <1054824142.1792.58.camel@mulgrave> Content-Type: text/plain Organization: Message-Id: <1054824389.13060.15.camel@markh1.pdx.osdl.net> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.4 Date: 05 Jun 2003 07:46:31 -0700 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2003-06-05 at 07:42, James Bottomley wrote: > On Thu, 2003-06-05 at 10:33, Mark Haverkamp wrote: > > On Thu, 2003-06-05 at 07:07, James Bottomley wrote: > > > On Tue, 2003-06-03 at 10:29, Mark Haverkamp wrote: > > > > A recent change to the megaraid driver to fix some memset calls resulted > > > > in overflowing the arrays being cleared and causing a system panic. > > > > This patch fixes the problem by making sure that the arrays being > > > > cleared are dimensioned to the correct size. The patch has been tested > > > > on osdl's stp machines that have megaraid controllers. > > > > > > This patch doesn't quite look like a fix to me: The megaraid mailboxes > > > are always >16 bytes *but* none of the setting commands is supposed to > > > touch any of the status parts (which begin at byte 15), so I don't see > > > how your patch would prevent a panic. > > > > In the memset cases, what fixed the panic was that the size of the > > raw_mbox automatic was set to 16 and the memset was using > > sizeof(mbox_t). I just increased the size of the raw_mbox so it > > wouldn't be overflowed. It sounds like, from what you are saying, that > > the size of raw_mbox should have been left at 16 and the memset changed > > to fill 16 bytes and not the sizeof(mbox_t). > > Ah, that's what I couldn't find in the source, thanks. > > My observation is that only the first 15 bytes of mbox may be altered by > the user thus, since the issue_scb.. functions copy the mbox anyway, > there's not much point allocating the full mbox (although there's no > harm in doing so). But rather than going back to the 16 byte > allocations and fixing the memset sizes, I think mbox_t should be split > into two pieces (and out and an in, with the issue_scb..() routines only > taking the in part) that way everything can be correctly written in > terms of sizeof. > > I was also separately worried about the memcpy in the issue_scb..() > routines which looks like it will set the mbox->busy parameter > (controlled by the driver) to zero. So I copied Atul to see if this is > a genuine problem or not. The issue_scb.. functions set the busy parameter to 1 so the memcpy of 16 should be OK. For instance in issue_scb_block, busy is preset in the raw_mbox before the memcpy. Mark. > > James -- Mark Haverkamp