From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: [PATCH][scsi-next] scsi: lpfc: fix null pointer dereference on nvmebuf Date: Wed, 11 Jul 2018 07:35:30 -0700 Message-ID: <1531319730.3260.1.camel@linux.vnet.ibm.com> References: <20180711134436.21963-1-colin.king@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20180711134436.21963-1-colin.king@canonical.com> Sender: linux-kernel-owner@vger.kernel.org To: Colin King , James Smart , Dick Kennedy , "Martin K . Petersen" , linux-scsi@vger.kernel.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-scsi@vger.kernel.org On Wed, 2018-07-11 at 14:44 +0100, Colin King wrote: > From: Colin Ian King > > The check of nvmebuf suggests that it can be null, however a recent > change dereferences it to determine oxid before it is null checked, > hence there is a potential null deference on the pointer.  Fix this > by performing the null check first.  Also remove the oxid from the > debug log message as this is no longer valid.  I considered an early > fetch of oxid if nvmebuf was valid, however, what oxid should be set > to if nvembuf is null could lead to an ambiguous logging of an > invalid > oxid, so I thought just removing it from the logging was the least > confusion solution. > > Detected by CoverityScan, CID#1471753 ("Dereference before null > check") > > Fixes: 68c9b55deea5 ("scsi: lpfc: Fix abort error path for NVMET") > Signed-off-by: Colin Ian King > --- >  drivers/scsi/lpfc/lpfc_nvmet.c | 8 ++++---- >  1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/scsi/lpfc/lpfc_nvmet.c > b/drivers/scsi/lpfc/lpfc_nvmet.c > index 22f8a204b69f..01652d9ac619 100644 > --- a/drivers/scsi/lpfc/lpfc_nvmet.c > +++ b/drivers/scsi/lpfc/lpfc_nvmet.c > @@ -1742,12 +1742,9 @@ lpfc_nvmet_unsol_ls_buffer(struct lpfc_hba > *phba, struct lpfc_sli_ring *pring, >   uint32_t *payload; >   uint32_t size, oxid, sid, rc; >   > - fc_hdr = (struct fc_frame_header *)(nvmebuf->hbuf.virt); > - oxid = be16_to_cpu(fc_hdr->fh_ox_id); > - >   if (!nvmebuf || !phba->targetport) { The !nvmebuf is a bogus check, isn't it? since nvmebuf is always obtained from a container_of, it can never be NULL. This would mean the rest of the contortions are unnecessary. James