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Date:      Sat, 11 Jan 2014 13:35:36 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r260541 - in head/sys/cam: . scsi
Message-ID:  <201401111335.s0BDZaFU070072@svn.freebsd.org>
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Author: mav
Date: Sat Jan 11 13:35:36 2014
New Revision: 260541
URL: http://svnweb.freebsd.org/changeset/base/260541

Log:
  Take additional reference on SCSI probe periph to cover its freeze count.
  
  Otherwise periph may be invalidated and freed before single-stepping freeze
  is dropped, causing use after free panic.

Modified:
  head/sys/cam/cam_periph.c
  head/sys/cam/cam_periph.h
  head/sys/cam/cam_xpt.c
  head/sys/cam/scsi/scsi_xpt.c

Modified: head/sys/cam/cam_periph.c
==============================================================================
--- head/sys/cam/cam_periph.c	Sat Jan 11 09:44:00 2014	(r260540)
+++ head/sys/cam/cam_periph.c	Sat Jan 11 13:35:36 2014	(r260541)
@@ -376,6 +376,17 @@ cam_periph_acquire(struct cam_periph *pe
 }
 
 void
+cam_periph_doacquire(struct cam_periph *periph)
+{
+
+	xpt_lock_buses();
+	KASSERT(periph->refcount >= 1,
+	    ("cam_periph_doacquire() with refcount == %d", periph->refcount));
+	periph->refcount++;
+	xpt_unlock_buses();
+}
+
+void
 cam_periph_release_locked_buses(struct cam_periph *periph)
 {
 

Modified: head/sys/cam/cam_periph.h
==============================================================================
--- head/sys/cam/cam_periph.h	Sat Jan 11 09:44:00 2014	(r260540)
+++ head/sys/cam/cam_periph.h	Sat Jan 11 13:35:36 2014	(r260541)
@@ -152,6 +152,7 @@ cam_status cam_periph_alloc(periph_ctor_
 struct cam_periph *cam_periph_find(struct cam_path *path, char *name);
 int		cam_periph_list(struct cam_path *, struct sbuf *);
 cam_status	cam_periph_acquire(struct cam_periph *periph);
+void		cam_periph_doacquire(struct cam_periph *periph);
 void		cam_periph_release(struct cam_periph *periph);
 void		cam_periph_release_locked(struct cam_periph *periph);
 void		cam_periph_release_locked_buses(struct cam_periph *periph);

Modified: head/sys/cam/cam_xpt.c
==============================================================================
--- head/sys/cam/cam_xpt.c	Sat Jan 11 09:44:00 2014	(r260540)
+++ head/sys/cam/cam_xpt.c	Sat Jan 11 13:35:36 2014	(r260541)
@@ -3156,9 +3156,7 @@ restart:
 			}
 			if (periph->flags & CAM_PERIPH_RUN_TASK)
 				break;
-			xpt_lock_buses();
-			periph->refcount++;	/* Unconditionally acquire */
-			xpt_unlock_buses();
+			cam_periph_doacquire(periph);
 			periph->flags |= CAM_PERIPH_RUN_TASK;
 			taskqueue_enqueue(xsoftc.xpt_taskq,
 			    &periph->periph_run_task);

Modified: head/sys/cam/scsi/scsi_xpt.c
==============================================================================
--- head/sys/cam/scsi/scsi_xpt.c	Sat Jan 11 09:44:00 2014	(r260540)
+++ head/sys/cam/scsi/scsi_xpt.c	Sat Jan 11 13:35:36 2014	(r260541)
@@ -888,12 +888,14 @@ again:
 				     /*timeout*/60 * 1000);
 			break;
 		}
+done:
 		/*
 		 * We'll have to do without, let our probedone
 		 * routine finish up for us.
 		 */
 		start_ccb->csio.data_ptr = NULL;
 		cam_freeze_devq(periph->path);
+		cam_periph_doacquire(periph);
 		probedone(periph, start_ccb);
 		return;
 	}
@@ -919,14 +921,7 @@ again:
 				     /*timeout*/60 * 1000);
 			break;
 		}
-		/*
-		 * We'll have to do without, let our probedone
-		 * routine finish up for us.
-		 */
-		start_ccb->csio.data_ptr = NULL;
-		cam_freeze_devq(periph->path);
-		probedone(periph, start_ccb);
-		return;
+		goto done;
 	}
 	case PROBE_SERIAL_NUM:
 	{
@@ -959,19 +954,13 @@ again:
 				     /*timeout*/60 * 1000);
 			break;
 		}
-		/*
-		 * We'll have to do without, let our probedone
-		 * routine finish up for us.
-		 */
-		start_ccb->csio.data_ptr = NULL;
-		cam_freeze_devq(periph->path);
-		probedone(periph, start_ccb);
-		return;
+		goto done;
 	}
 	default:
 		panic("probestart: invalid action state 0x%x\n", softc->action);
 	}
 	start_ccb->ccb_h.flags |= CAM_DEV_QFREEZE;
+	cam_periph_doacquire(periph);
 	xpt_action(start_ccb);
 }
 
@@ -1122,6 +1111,7 @@ probedone(struct cam_periph *periph, uni
 out:
 				/* Drop freeze taken due to CAM_DEV_QFREEZE */
 				cam_release_devq(path, 0, 0, 0, FALSE);
+				cam_periph_release_locked(periph);
 				return;
 			}
 			else if ((done_ccb->ccb_h.status & CAM_DEV_QFRZN) != 0)
@@ -1697,6 +1687,7 @@ probe_device_check:
 		CAM_DEBUG(periph->path, CAM_DEBUG_PROBE, ("Probe completed\n"));
 		/* Drop freeze taken due to CAM_DEV_QFREEZE flag set. */
 		cam_release_devq(path, 0, 0, 0, FALSE);
+		cam_periph_release_locked(periph);
 		cam_periph_invalidate(periph);
 		cam_periph_release_locked(periph);
 	} else {

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