linux-kernel - RE: [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from atomic_t to refcount

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Date:   Thu, 9 Mar 2017 07:18:29 +0000
From:   "Reshetova, Elena" <elena.reshetova@...el.com>
To:     Chris Leech <cleech@...hat.com>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux1394-devel@...ts.sourceforge.net" 
        <linux1394-devel@...ts.sourceforge.net>,
        "linux-bcache@...r.kernel.org" <linux-bcache@...r.kernel.org>,
        "linux-raid@...r.kernel.org" <linux-raid@...r.kernel.org>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "fcoe-devel@...n-fcoe.org" <fcoe-devel@...n-fcoe.org>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "open-iscsi@...glegroups.com" <open-iscsi@...glegroups.com>,
        "devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
        "target-devel@...r.kernel.org" <target-devel@...r.kernel.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        Hans Liljestrand <ishkamiel@...il.com>,
        Kees Cook <keescook@...omium.org>,
        David Windsor <dwindsor@...il.com>
Subject: RE: [PATCH 22/29] drivers, scsi: convert iscsi_task.refcount from
 atomic_t to refcount_t

> On Mon, Mar 06, 2017 at 04:21:09PM +0200, Elena Reshetova wrote:
> > refcount_t type and corresponding API should be
> > used instead of atomic_t when the variable is used as
> > a reference counter. This allows to avoid accidental
> > refcounter overflows that might lead to use-after-free
> > situations.
> >
> > Signed-off-by: Elena Reshetova <elena.reshetova@...el.com>
> > Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
> > Signed-off-by: Kees Cook <keescook@...omium.org>
> > Signed-off-by: David Windsor <dwindsor@...il.com>
> 
> This looks OK to me.
> 
> Acked-by: Chris Leech <cleech@...hat.com>

Thank you for review! Do you have a tree that can take this change? 

Best Regards,
Elena.

> 
> > ---
> >  drivers/scsi/libiscsi.c        | 8 ++++----
> >  drivers/scsi/qedi/qedi_iscsi.c | 2 +-
> >  include/scsi/libiscsi.h        | 3 ++-
> >  3 files changed, 7 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/scsi/libiscsi.c b/drivers/scsi/libiscsi.c
> > index 834d121..7eb1d2c 100644
> > --- a/drivers/scsi/libiscsi.c
> > +++ b/drivers/scsi/libiscsi.c
> > @@ -516,13 +516,13 @@ static void iscsi_free_task(struct iscsi_task *task)
> >
> >  void __iscsi_get_task(struct iscsi_task *task)
> >  {
> > -	atomic_inc(&task->refcount);
> > +	refcount_inc(&task->refcount);
> >  }
> >  EXPORT_SYMBOL_GPL(__iscsi_get_task);
> >
> >  void __iscsi_put_task(struct iscsi_task *task)
> >  {
> > -	if (atomic_dec_and_test(&task->refcount))
> > +	if (refcount_dec_and_test(&task->refcount))
> >  		iscsi_free_task(task);
> >  }
> >  EXPORT_SYMBOL_GPL(__iscsi_put_task);
> > @@ -744,7 +744,7 @@ __iscsi_conn_send_pdu(struct iscsi_conn *conn, struct
> iscsi_hdr *hdr,
> >  	 * released by the lld when it has transmitted the task for
> >  	 * pdus we do not expect a response for.
> >  	 */
> > -	atomic_set(&task->refcount, 1);
> > +	refcount_set(&task->refcount, 1);
> >  	task->conn = conn;
> >  	task->sc = NULL;
> >  	INIT_LIST_HEAD(&task->running);
> > @@ -1616,7 +1616,7 @@ static inline struct iscsi_task *iscsi_alloc_task(struct
> iscsi_conn *conn,
> >  	sc->SCp.phase = conn->session->age;
> >  	sc->SCp.ptr = (char *) task;
> >
> > -	atomic_set(&task->refcount, 1);
> > +	refcount_set(&task->refcount, 1);
> >  	task->state = ISCSI_TASK_PENDING;
> >  	task->conn = conn;
> >  	task->sc = sc;
> > diff --git a/drivers/scsi/qedi/qedi_iscsi.c b/drivers/scsi/qedi/qedi_iscsi.c
> > index b9f79d3..3895bd5 100644
> > --- a/drivers/scsi/qedi/qedi_iscsi.c
> > +++ b/drivers/scsi/qedi/qedi_iscsi.c
> > @@ -1372,7 +1372,7 @@ static void qedi_cleanup_task(struct iscsi_task *task)
> >  {
> >  	if (!task->sc || task->state == ISCSI_TASK_PENDING) {
> >  		QEDI_INFO(NULL, QEDI_LOG_IO, "Returning
> ref_cnt=%d\n",
> > -			  atomic_read(&task->refcount));
> > +			  refcount_read(&task->refcount));
> >  		return;
> >  	}
> >
> > diff --git a/include/scsi/libiscsi.h b/include/scsi/libiscsi.h
> > index b0e275d..24d74b5 100644
> > --- a/include/scsi/libiscsi.h
> > +++ b/include/scsi/libiscsi.h
> > @@ -29,6 +29,7 @@
> >  #include <linux/timer.h>
> >  #include <linux/workqueue.h>
> >  #include <linux/kfifo.h>
> > +#include <linux/refcount.h>
> >  #include <scsi/iscsi_proto.h>
> >  #include <scsi/iscsi_if.h>
> >  #include <scsi/scsi_transport_iscsi.h>
> > @@ -139,7 +140,7 @@ struct iscsi_task {
> >
> >  	/* state set/tested under session->lock */
> >  	int			state;
> > -	atomic_t		refcount;
> > +	refcount_t		refcount;
> >  	struct list_head	running;	/* running cmd list */
> >  	void			*dd_data;	/*
> driver/transport data */
> >  };
> > --
> > 2.7.4
> >