ses: close potential registration race

The slot and address fields have a small window of instability when
userspace can read them before initialization. Separate
enclosure_component
allocation from registration.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Jens Axboe <axboe@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>

1 files changed, 14 insertions, 7 deletions

diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index b7e79e7646ad..7dd9cf558380 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -423,16 +423,23 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
                             type_ptr[0] == ENCLOSURE_COMPONENT_ARRAY_DEVICE) {
 
                                 if (create)
-                                        ecomp = enclosure_component_register(edev,
-                                                                             components++,
-                                                                             type_ptr[0],
-                                                                             name);
+                                        ecomp = enclosure_component_alloc(
+                                                edev,
+                                                components++,
+                                                type_ptr[0],
+                                                name);
                                 else
                                         ecomp = &edev->component[components++];
 
-                                if (!IS_ERR(ecomp) && addl_desc_ptr)
-                                        ses_process_descriptor(ecomp,
-                                                               addl_desc_ptr);
+                                if (!IS_ERR(ecomp)) {
+                                        if (addl_desc_ptr)
+                                                ses_process_descriptor(
+                                                        ecomp,
+                                                        addl_desc_ptr);
+                                        if (create)
+                                                enclosure_component_register(
+                                                        ecomp);
+                                }
                         }
                         if (desc_ptr)
                                 desc_ptr += len;