vfio-ccw: plug memory leak while getting region info

vfio_get_dev_region_info() unconditionally allocates memory
for a passed-in vfio_region_info structure (and does not re-use
an already allocated structure). Therefore, we have to free
the structure we pass to that function in vfio_ccw_get_region()
for every region we successfully obtained information for.

Fixes: 8fadea24de4e ("vfio-ccw: support async command subregion")
Fixes: 46ea3841edaf ("vfio-ccw: Add support for the schib region")
Fixes: f030532f2ad6 ("vfio-ccw: Add support for the CRW region and IRQ")
Reported-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200928101701.13540-1-cohuck@redhat.com>

hw/vfio/ccw.c

@@ -491,6 +491,7 @@ static void vfio_ccw_get_region(VFIOCCWDevice *vcdev, Error **errp)
 
     vcdev->io_region_offset = info->offset;
     vcdev->io_region = g_malloc0(info->size);
+    g_free(info);
 
     /* check for the optional async command region */
     ret = vfio_get_dev_region_info(vdev, VFIO_REGION_TYPE_CCW,
@@ -503,6 +504,7 @@ static void vfio_ccw_get_region(VFIOCCWDevice *vcdev, Error **errp)
         }
         vcdev->async_cmd_region_offset = info->offset;
         vcdev->async_cmd_region = g_malloc0(info->size);
+        g_free(info);
     }
 
     ret = vfio_get_dev_region_info(vdev, VFIO_REGION_TYPE_CCW,
@@ -515,6 +517,7 @@ static void vfio_ccw_get_region(VFIOCCWDevice *vcdev, Error **errp)
         }
         vcdev->schib_region_offset = info->offset;
         vcdev->schib_region = g_malloc(info->size);
+        g_free(info);
     }
 
     ret = vfio_get_dev_region_info(vdev, VFIO_REGION_TYPE_CCW,
@@ -528,9 +531,9 @@ static void vfio_ccw_get_region(VFIOCCWDevice *vcdev, Error **errp)
         }
         vcdev->crw_region_offset = info->offset;
         vcdev->crw_region = g_malloc(info->size);
+        g_free(info);
     }
 
-    g_free(info);
     return;
 
 out_err: