scsi_dh: fix use-after-free when removing scsi device
The commit 1bab0de0274f ("dm-mpath, scsi_dh: don't let dm detach device
handlers") removed reference counting of attached scsi device handler.
As a result, handler data is freed immediately via scsi_dh->detach()
in the context of scsi_remove_device() where activation request can be
still in flight.
This patch moves scsi_dh_handler_detach() to sdev releasing function,
scsi_device_dev_release_usercontext(), at that point the device
is already in quiesced state.
Fixes: 1bab0de0274f ("dm-mpath, scsi_dh: don't let dm detach device handlers")
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <JBottomley@Odin.com>
diff --git a/drivers/scsi/scsi_dh.c b/drivers/scsi/scsi_dh.c
index 0a2168e..cb78388 100644
--- a/drivers/scsi/scsi_dh.c
+++ b/drivers/scsi/scsi_dh.c
@@ -232,10 +232,14 @@
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 @@
/* 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 @@
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);