[GIT PULL] SCSI fixes for 4.3-rc4

[James Bottomley <James.Bottomley@HansenPartnership.com>]

This is three essential bug fixes for various SCSI parts.  The only
affected users are SCSI multi-path via device handler (basically all the
enterprise) and mvsas users.  The dh bugs are an async entanglement in
boot resulting in a serious WARN_ON trip and a use after free on remove
leading to a crash with strict memory accounting.  The mvsas bug
manifests as a null deref oops but only on abort sequences; however,
these can commonly occur with SATA attached devices, hence the fix.

The patch is available here:

git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi.git scsi-fixes

The short changelog is:

Christoph Hellwig (1):
      scsi_dh: don't try to load a device handler during async probing

Dāvis Mosāns (1):
      mvsas: Fix NULL pointer dereference in mvs_slot_task_free

Junichi Nomura (1):
      scsi_dh: fix use-after-free when removing scsi device

And the diffstat:

 drivers/scsi/mvsas/mv_sas.c | 2 ++
 drivers/scsi/scsi_dh.c      | 8 ++++++--
 drivers/scsi/scsi_priv.h    | 2 ++
 drivers/scsi/scsi_sysfs.c   | 2 ++
 4 files changed, 12 insertions(+), 2 deletions(-)

With full diff below.

James

---

diff --git a/drivers/scsi/mvsas/mv_sas.c b/drivers/scsi/mvsas/mv_sas.c
index 454536c..9c78074 100644
--- a/drivers/scsi/mvsas/mv_sas.c
+++ b/drivers/scsi/mvsas/mv_sas.c
@@ -887,6 +887,8 @@ static void mvs_slot_free(struct mvs_info *mvi, u32 rx_desc)
 static void mvs_slot_task_free(struct mvs_info *mvi, struct sas_task *task,
 			  struct mvs_slot_info *slot, u32 slot_idx)
 {
+	if (!slot)
+		return;
 	if (!slot->task)
 		return;
 	if (!sas_protocol_ata(task->task_proto))
diff --git a/drivers/scsi/scsi_dh.c b/drivers/scsi/scsi_dh.c
index 0a2168e..e7649ed 100644
--- a/drivers/scsi/scsi_dh.c
+++ b/drivers/scsi/scsi_dh.c
@@ -226,16 +226,20 @@ int scsi_dh_add_device(struct scsi_device *sdev)
 
 	drv = scsi_dh_find_driver(sdev);
 	if (drv)
-		devinfo = scsi_dh_lookup(drv);
+		devinfo = __scsi_dh_lookup(drv);
 	if (devinfo)
 		err = scsi_dh_handler_attach(sdev, devinfo);
 	return err;
 }
 
-void scsi_dh_remove_device(struct scsi_device *sdev)
+void scsi_dh_release_device(struct scsi_device *sdev)
 {
 	if (sdev->handler)
 		scsi_dh_handler_detach(sdev);
+}
+
+void scsi_dh_remove_device(struct scsi_device *sdev)
+{
 	device_remove_file(&sdev->sdev_gendev, &scsi_dh_state_attr);
 }
 
diff --git a/drivers/scsi/scsi_priv.h b/drivers/scsi/scsi_priv.h
index 644bb73..4d01cdb 100644
--- a/drivers/scsi/scsi_priv.h
+++ b/drivers/scsi/scsi_priv.h
@@ -173,9 +173,11 @@ extern struct async_domain scsi_sd_probe_domain;
 /* scsi_dh.c */
 #ifdef CONFIG_SCSI_DH
 int scsi_dh_add_device(struct scsi_device *sdev);
+void scsi_dh_release_device(struct scsi_device *sdev);
 void scsi_dh_remove_device(struct scsi_device *sdev);
 #else
 static inline int scsi_dh_add_device(struct scsi_device *sdev) { return 0; }
+static inline void scsi_dh_release_device(struct scsi_device *sdev) { }
 static inline void scsi_dh_remove_device(struct scsi_device *sdev) { }
 #endif
 
diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index b333389..dff8faf 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -399,6 +399,8 @@ static void scsi_device_dev_release_usercontext(struct work_struct *work)
 
 	sdev = container_of(work, struct scsi_device, ew.work);
 
+	scsi_dh_release_device(sdev);
+
 	parent = sdev->sdev_gendev.parent;
 
 	spin_lock_irqsave(sdev->host->host_lock, flags);