4.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Johannes Thumshirn <jthumshirn@xxxxxxx> commit 68c59fcea1f2c6a54c62aa896cc623c1b5bc9b47 upstream. SG_DXFER_FROM_DEV transfers do not necessarily have a dxferp as we set it to NULL for the old sg_io read/write interface, 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") 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: Douglas Gilbert <dgilbert@xxxxxxxxxxxx> Reviewed-by: Hannes Reinecke <hare@xxxxxxxx> Tested-by: Chris Clayton <chris2553@xxxxxxxxxxxxxx> Acked-by: 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 | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -758,8 +758,11 @@ static bool sg_is_valid_dxfer(sg_io_hdr_ if (hp->dxferp || hp->dxfer_len > 0) return false; return true; - case SG_DXFER_TO_DEV: case SG_DXFER_FROM_DEV: + if (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;