| Message ID | 1494450443-2921-1-git-send-email-longli@exchange.microsoft.com (mailing list archive) |
|---|---|
| State | Deferred, archived |
| Headers | show |
> -----Original Message----- > From: Long Li [mailto:longli@exchange.microsoft.com] > Sent: Wednesday, May 10, 2017 2:07 PM > To: James E.J. Bottomley <jejb@linux.vnet.ibm.com>; Martin K. Petersen > <martin.petersen@oracle.com>; linux-scsi@vger.kernel.org; linux- > kernel@vger.kernel.org > Cc: Long Li <longli@microsoft.com> > Subject: [PATCH] scsi: zero per-cmd driver data for each MQ I/O > > From: Long Li <longli@microsoft.com> > > Lower layer driver may not initialize private data before use. Zero them out > to prevent use of stale data. > > Signed-off-by: Long Li <longli@microsoft.com> Can someone help review this patch? > --- > drivers/scsi/scsi_lib.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index > 19125d7..a821593 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1850,7 +1850,7 @@ static int scsi_mq_prep_fn(struct request *req) > > /* zero out the cmd, except for the embedded scsi_request */ > memset((char *)cmd + sizeof(cmd->req), 0, > - sizeof(*cmd) - sizeof(cmd->req)); > + sizeof(*cmd) - sizeof(cmd->req) + > + shost->hostt->cmd_size); > > req->special = cmd; > > -- > 2.7.4
On Wed, 2017-05-10 at 14:07 -0700, Long Li wrote: > From: Long Li <longli@microsoft.com> > > Lower layer driver may not initialize private data before use. Zero them > out to prevent use of stale data. > > Signed-off-by: Long Li <longli@microsoft.com> > --- > drivers/scsi/scsi_lib.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c > index 19125d7..a821593 100644 > --- a/drivers/scsi/scsi_lib.c > +++ b/drivers/scsi/scsi_lib.c > @@ -1850,7 +1850,7 @@ static int scsi_mq_prep_fn(struct request *req) > > /* zero out the cmd, except for the embedded scsi_request */ > memset((char *)cmd + sizeof(cmd->req), 0, > - sizeof(*cmd) - sizeof(cmd->req)); > + sizeof(*cmd) - sizeof(cmd->req) + shost->hostt->cmd_size); > > req->special = cmd; Hello Long, Sorry but this patch looks wrong to me. Since scsi_mq_prep_fn() is called after scsi_req_init(), erasing struct scsi_request from scsi_mq_prep_fn() will erase the values that were set by scsi_req_init(). That includes information like the pointer to the SCSI CDB and the CDB itself. See e.g. scsi_execute(). Did you come up with this patch after source reading or did you come up with this patch while chasing a bug? Thanks, Bart.
> -----Original Message----- > From: Long Li > Sent: Monday, May 15, 2017 3:48 PM > To: Long Li <longli@microsoft.com>; James E.J. Bottomley > <jejb@linux.vnet.ibm.com>; Martin K. Petersen > <martin.petersen@oracle.com>; linux-scsi@vger.kernel.org; linux- > kernel@vger.kernel.org > Cc: KY Srinivasan <kys@microsoft.com>; Stephen Hemminger > <sthemmin@microsoft.com> > Subject: RE: [PATCH] scsi: zero per-cmd driver data for each MQ I/O > > > -----Original Message----- > > From: Long Li [mailto:longli@exchange.microsoft.com] > > Sent: Wednesday, May 10, 2017 2:07 PM > > To: James E.J. Bottomley <jejb@linux.vnet.ibm.com>; Martin K. Petersen > > <martin.petersen@oracle.com>; linux-scsi@vger.kernel.org; linux- > > kernel@vger.kernel.org > > Cc: Long Li <longli@microsoft.com> > > Subject: [PATCH] scsi: zero per-cmd driver data for each MQ I/O > > > > From: Long Li <longli@microsoft.com> > > > > Lower layer driver may not initialize private data before use. Zero them out > > to prevent use of stale data. > > > > Signed-off-by: Long Li <longli@microsoft.com> > > Can someone help review this patch? Reviewed-by: K. Y. Srinivasan <kys@microsoft.com> > > > --- > > drivers/scsi/scsi_lib.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index > > 19125d7..a821593 100644 > > --- a/drivers/scsi/scsi_lib.c > > +++ b/drivers/scsi/scsi_lib.c > > @@ -1850,7 +1850,7 @@ static int scsi_mq_prep_fn(struct request *req) > > > > /* zero out the cmd, except for the embedded scsi_request */ > > memset((char *)cmd + sizeof(cmd->req), 0, > > - sizeof(*cmd) - sizeof(cmd->req)); > > + sizeof(*cmd) - sizeof(cmd->req) + > > + shost->hostt->cmd_size); > > > > req->special = cmd; > > > > -- > > 2.7.4
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 19125d7..a821593 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1850,7 +1850,7 @@ static int scsi_mq_prep_fn(struct request *req) /* zero out the cmd, except for the embedded scsi_request */ memset((char *)cmd + sizeof(cmd->req), 0, - sizeof(*cmd) - sizeof(cmd->req)); + sizeof(*cmd) - sizeof(cmd->req) + shost->hostt->cmd_size); req->special = cmd;