[PATCH 3.18 67/68] scsi: sg: fix static checker warning in sg_is_valid_dxfer

From: Greg Kroah-Hartman
Date: Mon Mar 19 2018 - 16:36:18 EST


3.18-stable review patch. If anyone has any objections, please let me know.

------------------

From: Johannes Thumshirn <jthumshirn@xxxxxxx>

commit 14074aba4bcda3764c9a702b276308b89901d5b6 upstream.

dxfer_len is an unsigned int and we always assign a value > 0 to it, so
it doesn't make any sense to check if it is < 0. We can't really check
dxferp as well as we have both NULL and not NULL cases in the possible
call paths.

So just return true for SG_DXFER_FROM_DEV transfer in
sg_is_valid_dxfer().

Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Reported-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Douglas Gilbert <dgilbert@xxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/scsi/sg.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -770,8 +770,11 @@ static bool sg_is_valid_dxfer(sg_io_hdr_
return false;
return true;
case SG_DXFER_FROM_DEV:
- if (hp->dxfer_len < 0)
- return false;
+ /*
+ * for SG_DXFER_FROM_DEV we always set dxfer_len to > 0. dxferp
+ * can either be NULL or != NULL so there's no point in checking
+ * it either. So just return true.
+ */
return true;
case SG_DXFER_TO_DEV:
case SG_DXFER_TO_FROM_DEV: