From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938162AbXG0XPE (ORCPT ); Fri, 27 Jul 2007 19:15:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1765640AbXG0XOx (ORCPT ); Fri, 27 Jul 2007 19:14:53 -0400 Received: from ik-out-1112.google.com ([66.249.90.176]:48317 "EHLO ik-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1764912AbXG0XOv (ORCPT ); Fri, 27 Jul 2007 19:14:51 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:from:to:subject:date:user-agent:cc:references:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:message-id; b=E1zhvahrk46vFd7FIWzXTcrYirhKx3v2/SEPbrbFhmsyg3EknL/xFcpes8NAGkod6H1L3+4ri8+4bI7mp0MAt5CWv+3dKqp/0fOlJwF2Xtuii0f/USTDMIs6PG9vyXWbIy6cEY1QeW0lDuWKge8lIsy4nr95iOMGvaHhvw5+rHE= From: Jesper Juhl To: James Bottomley Subject: Re: [PATCH][sas] Fix potential NULL pointer dereference bug in sas_smp_get_phy_events() Date: Sat, 28 Jul 2007 01:13:33 +0200 User-Agent: KMail/1.9.7 Cc: linux-scsi@vger.kernel.org, Luben Tuikov , Linux Kernel Mailing List , Jesper Juhl References: <200707272327.57356.jesper.juhl@gmail.com> <1185577372.3434.29.camel@localhost.localdomain> In-Reply-To: <1185577372.3434.29.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200707280113.33766.jesper.juhl@gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On 28/07/07, James Bottomley wrote: > On Fri, 2007-07-27 at 23:27 +0200, Jesper Juhl wrote: > > In sas_smp_get_phy_events() we never test if the call to > > alloc_smp_req(RPEL_REQ_SIZE) succeeds or fails. That means we run > > the risk of dereferencing a NULL pointer if it does fail. Far > > better to test if we got NULL back and in that case return -ENOMEM > > just as we already do for the other memory allocation in that > > function. > > This patch reworks the memory allocation a bit to deal with it > > (compile tested only). > > > > > > Signed-off-by: Jesper Juhl > > --- > > > > drivers/scsi/libsas/sas_expander.c | 11 +++++++++-- > > 1 files changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c > > index b500f0c..85f5145 100644 > > --- a/drivers/scsi/libsas/sas_expander.c > > +++ b/drivers/scsi/libsas/sas_expander.c > > @@ -507,14 +507,21 @@ static int sas_dev_present_in_domain(struct asd_sas_port *port, > > int sas_smp_get_phy_events(struct sas_phy *phy) > > { > > int res; > > + u8 *req; > > + u8 *resp; > > struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent); > > struct domain_device *dev = sas_find_dev_by_rphy(rphy); > > - u8 *req = alloc_smp_req(RPEL_REQ_SIZE); > > - u8 *resp = kzalloc(RPEL_RESP_SIZE, GFP_KERNEL); > > > > + resp = kzalloc(RPEL_RESP_SIZE, GFP_KERNEL); > > Actually, this should be alloc_smp_resp(RPEL_RESP_SIZE); > > > if (!resp) > > return -ENOMEM; > > > > + req = alloc_smp_req(RPEL_REQ_SIZE); > > + if (!req) { > > + res = -ENOMEM; > > + goto out; > > + } > > Just for the sake of being the same as all the rest of the code, the > sequence should be > > req = alloc_smp_req(xxx_REQ_SIZE); > if (!req) > return -ENOMEM; > > resp = alloc_smp_resp(xxx_RESP_SIZE); > if (!resp) { > kfree(req); > return -ENOMEM; > } > > (allocate request then response). > Fair enough. It makes the code a bit larger though : My way, as per the original patch: text data bss dec hex filename 13820 0 8 13828 3604 drivers/scsi/libsas/sas_expander.o Your way, as per this patch: text data bss dec hex filename 13832 0 8 13840 3610 drivers/scsi/libsas/sas_expander.o I hope this patch is acceptable : In sas_smp_get_phy_events() we never test if the call to alloc_smp_req(RPEL_REQ_SIZE) succeeds or fails. That means we run the risk of dereferencing a NULL pointer if it does fail. Far better to test if we got NULL back and in that case return -ENOMEM just as we already do for the other memory allocation in that function. This patch should take care of it (compile tested only). Signed-off-by: Jesper Juhl --- drivers/scsi/libsas/sas_expander.c | 13 ++++++++++--- 1 files changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/libsas/sas_expander.c b/drivers/scsi/libsas/sas_expander.c index b500f0c..e98d2b9 100644 --- a/drivers/scsi/libsas/sas_expander.c +++ b/drivers/scsi/libsas/sas_expander.c @@ -507,14 +507,21 @@ static int sas_dev_present_in_domain(struct asd_sas_port *port, int sas_smp_get_phy_events(struct sas_phy *phy) { int res; + u8 *req; + u8 *resp; struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent); struct domain_device *dev = sas_find_dev_by_rphy(rphy); - u8 *req = alloc_smp_req(RPEL_REQ_SIZE); - u8 *resp = kzalloc(RPEL_RESP_SIZE, GFP_KERNEL); - if (!resp) + req = alloc_smp_req(RPEL_REQ_SIZE); + if (!req) return -ENOMEM; + resp = alloc_smp_resp(RPEL_RESP_SIZE); + if (!resp) { + kfree(req); + return -ENOMEM; + } + req[1] = SMP_REPORT_PHY_ERR_LOG; req[9] = phy->number; > It looks like disc_resp could use a little love too (it's using the req > alloc routines). > I'll take a look at that later. -- Jesper Juhl Don't top-post http://www.catb.org/~esr/jargon/html/T/top-post.html Plain text mails only, please http://www.expita.com/nomime.html