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>

diff --git a/drivers/misc/enclosure.c b/drivers/misc/enclosure.c
index 180a5442fd4b8d0522cec564ed58cec51386b188..e18278aa6bbb9e0efe5735371d20e8a3340eac80 100644 (file)
--- a/drivers/misc/enclosure.c
+++ b/drivers/misc/enclosure.c
@@ -273,27 +273,26 @@ enclosure_component_find_by_name(struct enclosure_device *edev,
 static const struct attribute_group *enclosure_component_groups[];
 
 /**
- * enclosure_component_register - add a particular component to an enclosure
+ * enclosure_component_alloc - prepare a new enclosure component
  * @edev:      the enclosure to add the component
  * @num:       the device number
  * @type:      the type of component being added
  * @name:      an optional name to appear in sysfs (leave NULL if none)
  *
- * Registers the component.  The name is optional for enclosures that
- * give their components a unique name.  If not, leave the field NULL
- * and a name will be assigned.
+ * The name is optional for enclosures that give their components a unique
+ * name.  If not, leave the field NULL and a name will be assigned.
  *
  * Returns a pointer to the enclosure component or an error.
  */
 struct enclosure_component *
-enclosure_component_register(struct enclosure_device *edev,
-                            unsigned int number,
-                            enum enclosure_component_type type,
-                            const char *name)
+enclosure_component_alloc(struct enclosure_device *edev,
+                         unsigned int number,
+                         enum enclosure_component_type type,
+                         const char *name)
 {
        struct enclosure_component *ecomp;
        struct device *cdev;
-       int err, i;
+       int i;
        char newname[COMPONENT_NAME_SIZE];
 
        if (number >= edev->components)
@@ -327,14 +326,30 @@ enclosure_component_register(struct enclosure_device *edev,
        cdev->release = enclosure_component_release;
        cdev->groups = enclosure_component_groups;
 
+       return ecomp;
+}
+EXPORT_SYMBOL_GPL(enclosure_component_alloc);
+
+/**
+ * enclosure_component_register - publishes an initialized enclosure component
+ * @ecomp:     component to add
+ *
+ * Returns 0 on successful registration, releases the component otherwise
+ */
+int enclosure_component_register(struct enclosure_component *ecomp)
+{
+       struct device *cdev;
+       int err;
+
+       cdev = &ecomp->cdev;
        err = device_register(cdev);
        if (err) {
                ecomp->number = -1;
                put_device(cdev);
-               return ERR_PTR(err);
+               return err;
        }
 
-       return ecomp;
+       return 0;
 }
 EXPORT_SYMBOL_GPL(enclosure_component_register);
 

diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index b7e79e7646ad2a82aa0e37c43671f3c2191beb4f..7dd9cf5583802aeb0e1073ba4eca13d1f4124688 100644 (file)
--- 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;

diff --git a/include/linux/enclosure.h b/include/linux/enclosure.h
index 9a33c5f7e1265fd23ee74462e3e93944cf414997..a835d335b9241b087457be282ad2c61159941e0d 100644 (file)
--- a/include/linux/enclosure.h
+++ b/include/linux/enclosure.h
@@ -120,8 +120,9 @@ enclosure_register(struct device *, const char *, int,
                   struct enclosure_component_callbacks *);
 void enclosure_unregister(struct enclosure_device *);
 struct enclosure_component *
-enclosure_component_register(struct enclosure_device *, unsigned int,
-                                enum enclosure_component_type, const char *);
+enclosure_component_alloc(struct enclosure_device *, unsigned int,
+                         enum enclosure_component_type, const char *);
+int enclosure_component_register(struct enclosure_component *);
 int enclosure_add_device(struct enclosure_device *enclosure, int component,
                         struct device *dev);
 int enclosure_remove_device(struct enclosure_device *, struct device *);