From mboxrd@z Thu Jan 1 00:00:00 1970 From: Douglas Gilbert Subject: Re: [PATCH] scsi: sg: fix SG_DXFER_FROM_DEV transfers Date: Thu, 6 Jul 2017 14:47:22 -0400 Message-ID: <54abb58b-3fe6-8e64-91aa-182fbef93467@interlog.com> References: <20170705134934.1703-1-jthumshirn@suse.de> Reply-To: dgilbert@interlog.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170705134934.1703-1-jthumshirn@suse.de> Content-Language: en-CA Sender: linux-kernel-owner@vger.kernel.org To: Johannes Thumshirn , "Martin K . Petersen" Cc: Linux SCSI Mailinglist , Linux Kernel Mailinglist , Chris Clayton List-Id: linux-scsi@vger.kernel.org On 2017-07-05 09:49 AM, Johannes Thumshirn wrote: > SG_DXFER_FROM_DEV transfers do not have a dxferp as we set it to NULL, > but must have a length bigger than 0. This fixes a regression introduced > by commit 28676d869bbb ("scsi: sg: check for valid direction before > starting the request") It is not clear to me that dxferp is set to NULL for the newer sg_v3 interface. In the sg.c source of lk 4.12.0 around line 654 (in the sg_write(...) function) only the older interface passes through; the newer interface bypasses that section with a 'return sg_new_write(...)' on line 606. Can you check your patch with one of the utilities from sg3_utils such as sg_inq which will use SG_DXFER_FROM_DEV with the newer interface? BTW I'm not sure why dxferp is set to NULL for SG_DXFER_FROM_DEV transfers; perhaps some magic done by the block layer. Maybe a comment in the code (e.g. on line 654) would help. Also sg_is_valid_dxfer() is only called once and is more complex than it looks; so perhaps it could be inlined back in sg_common_write(). Doug Gilbert > Signed-off-by: Johannes Thumshirn > Fixes: 28676d869bbb ("scsi: sg: check for valid direction before starting the request") > Reported-by: Chris Clayton > Tested-by: Chris Clayton > Cc: Doug Gilbert > --- > drivers/scsi/sg.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c > index 21225d62b0c1..3c91593260aa 100644 > --- a/drivers/scsi/sg.c > +++ b/drivers/scsi/sg.c > @@ -758,8 +758,11 @@ static bool sg_is_valid_dxfer(sg_io_hdr_t *hp) > if (hp->dxferp || hp->dxfer_len > 0) > return false; > return true; > - case SG_DXFER_TO_DEV: > case SG_DXFER_FROM_DEV: > + if (hp->dxferp || hp->dxfer_len < 0) > + return false; > + return true; > + case SG_DXFER_TO_DEV: > case SG_DXFER_TO_FROM_DEV: > if (!hp->dxferp || hp->dxfer_len == 0) > return false; >