s390/pci: Fix leak of struct zpci_dev when zpci_add_device() fails

Prior to commit 0467cdde8c43 ("s390/pci: Sort PCI functions prior to
creating virtual busses") the IOMMU was initialized and the device was
registered as part of zpci_create_device() with the struct zpci_dev
freed if either resulted in an error. With that commit this was moved
into a separate function called zpci_add_device().

While this new function logs when adding failed, it expects the caller
not to use and to free the struct zpci_dev on error. This difference
between it and zpci_create_device() was missed while changing the
callers and the incompletely initialized struct zpci_dev may get used in
zpci_scan_configured_device in the error path. This then leads to
a crash due to the device not being registered with the zbus. It was
also not freed in this case. Fix this by handling the error return of
zpci_add_device(). Since in this case the zdev was not added to the
zpci_list it can simply be discarded and freed. Also make this more
explicit by moving the kref_init() into zpci_add_device() and document
that zpci_zdev_get()/zpci_zdev_put() must be used after adding.

Cc: stable@vger.kernel.org
Fixes: 0467cdde8c43 ("s390/pci: Sort PCI functions prior to creating virtual busses")
Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index b7efa96776eac28bb6b947082d64fca67cbe79ea..6a011d040dfef14a194299be0f7c41b560cb879a 100644 (file)
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -776,8 +776,9 @@ int zpci_hot_reset_device(struct zpci_dev *zdev)
  * @fh: Current Function Handle of the device to be created
  * @state: Initial state after creation either Standby or Configured
  *
- * Creates a new zpci device and adds it to its, possibly newly created, zbus
- * as well as zpci_list.
+ * Allocates a new struct zpci_dev and queries the platform for its details.
+ * If successful the device can subsequently be added to the zPCI subsystem
+ * using zpci_add_device().
  *
  * Returns: the zdev on success or an error pointer otherwise
  */
@@ -800,7 +801,6 @@ struct zpci_dev *zpci_create_device(u32 fid, u32 fh, enum zpci_state state)
                goto error;
        zdev->state =  state;
 
-       kref_init(&zdev->kref);
        mutex_init(&zdev->state_lock);
        mutex_init(&zdev->fmb_lock);
        mutex_init(&zdev->kzdev_lock);
@@ -813,6 +813,17 @@ error:
        return ERR_PTR(rc);
 }
 
+/**
+ * zpci_add_device() - Add a previously created zPCI device to the zPCI subsystem
+ * @zdev: The zPCI device to be added
+ *
+ * A struct zpci_dev is added to the zPCI subsystem and to a virtual PCI bus creating
+ * a new one as necessary. A hotplug slot is created and events start to be handled.
+ * If successful from this point on zpci_zdev_get() and zpci_zdev_put() must be used.
+ * If adding the struct zpci_dev fails the device was not added and should be freed.
+ *
+ * Return: 0 on success, or an error code otherwise
+ */
 int zpci_add_device(struct zpci_dev *zdev)
 {
        int rc;
@@ -826,6 +837,7 @@ int zpci_add_device(struct zpci_dev *zdev)
        if (rc)
                goto error_destroy_iommu;
 
+       kref_init(&zdev->kref);
        spin_lock(&zpci_list_lock);
        list_add_tail(&zdev->entry, &zpci_list);
        spin_unlock(&zpci_list_lock);
@@ -1118,7 +1130,8 @@ static void zpci_add_devices(struct list_head *scan_list)
        list_sort(NULL, scan_list, &zpci_cmp_rid);
        list_for_each_entry_safe(zdev, tmp, scan_list, entry) {
                list_del_init(&zdev->entry);
-               zpci_add_device(zdev);
+               if (zpci_add_device(zdev))
+                       kfree(zdev);
        }
 }
 

diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
index 47f934f4e828e9ac6f8cae46474346d14fb5375b..7f7b732b3f3efaecf9fd17420f911414d9d0ef7b 100644 (file)
--- a/arch/s390/pci/pci_event.c
+++ b/arch/s390/pci/pci_event.c
@@ -340,7 +340,10 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
                        zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_CONFIGURED);
                        if (IS_ERR(zdev))
                                break;
-                       zpci_add_device(zdev);
+                       if (zpci_add_device(zdev)) {
+                               kfree(zdev);
+                               break;
+                       }
                } else {
                        /* the configuration request may be stale */
                        if (zdev->state != ZPCI_FN_STATE_STANDBY)
@@ -354,7 +357,10 @@ static void __zpci_event_availability(struct zpci_ccdf_avail *ccdf)
                        zdev = zpci_create_device(ccdf->fid, ccdf->fh, ZPCI_FN_STATE_STANDBY);
                        if (IS_ERR(zdev))
                                break;
-                       zpci_add_device(zdev);
+                       if (zpci_add_device(zdev)) {
+                               kfree(zdev);
+                               break;
+                       }
                } else {
                        zpci_update_fh(zdev, ccdf->fh);
                }