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 <jthumshirn@xxxxxxx>
Fixes: 28676d869bbb ("scsi: sg: check for valid direction before starting the request")
Reported-by: Chris Clayton <chris2553@xxxxxxxxxxxxxx>
Tested-by: Chris Clayton <chris2553@xxxxxxxxxxxxxx>
Cc: Doug Gilbert <dgilbert@xxxxxxxxxxxx>
---
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;
