From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4EDA8FA9.8020004@linux.vnet.ibm.com> Date: Sat, 03 Dec 2011 22:07:53 +0100 From: Steffen Maier MIME-Version: 1.0 To: Stratos Psomadakis CC: linux-kernel@vger.kernel.org, stable@vger.kernel.org, gregkh@suse.de, linux-scsi@vger.kernel.org, JBottomley@parallels.com, matthew@wil.cx, Martin.vGagern@gmx.net, kernel@gentoo.org Subject: Re: [SCSI] NULL pointer dereference in sym53c8xx (bisected) References: <4ED8EE1C.4090404@gentoo.org> In-Reply-To: <4ED8EE1C.4090404@gentoo.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: On 12/02/2011 04:26 PM, Stratos Psomadakis wrote: > After upstream commit 4e6c82b3614a18740ef63109d58743a359266daf ([SCSI] > fix WARNING: at drivers/scsi/scsi_lib.c:1704), which is also included in > 3.0-stable and 3.1-stable kernels, the kernel fails to boot (NULL > pointer dereference in sym53c8xx_slave_destroy). > > Bug report at the Gentoo Bugzilla (reported and bisected by Martin von > Gagern). [1] (stack trace [2]) > > I think that the problem is that (after commit 4e6c82b) > __scsi_remove_device() is called if slave_alloc() in scsi_alloc_sdev() > fails. But __scsi_remove_device() calls slave_destroy(), which (I think) > doesn't make much sense (ie to call slave_destroy() when slave_alloc() > fails). > > For sym53c8xx, this results in a NULL pointer dereference (struct > sym_lcb pointer) in slave_destroy(). > > [1] https://bugs.gentoo.org/show_bug.cgi?id=392567 > [2] https://392567.bugs.gentoo.org/attachment.cgi?id=294381 To me this looks like the same thing we encountered in the zfcp LLD: http://www.spinics.net/lists/linux-scsi/msg55575.html James explained the pairing of slave_alloc and slave_destroy even if slave_alloc returned early in which case slave_destroy needs to cope with that: http://www.spinics.net/lists/linux-scsi/msg55449.html HTH Steffen Linux on System z Development IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martin Jetter Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294