vhost: fix error handling in RESET_OWNER ioctl

RESET_OWNER ioctl would leave the fd in a bad state if
memory allocation failed: device is stopped
but owner is not reset. Make state changes
after allocating memory, such that a failed
ioctl has no effect.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 7 insertions, 9 deletions

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 6dcd81c87432..749b5ab5bfbb 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -386,21 +386,19 @@ err_mm:
         return err;
 }
 
-/* Caller should have device mutex */
-long vhost_dev_reset_owner(struct vhost_dev *dev)
+struct vhost_memory *vhost_dev_reset_owner_prepare(void)
 {
-        struct vhost_memory *memory;
-
-        /* Restore memory to default empty mapping. */
-        memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
-        if (!memory)
-                return -ENOMEM;
+        return kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL);
+}
 
+/* Caller should have device mutex */
+void vhost_dev_reset_owner(struct vhost_dev *dev, struct vhost_memory *memory)
+{
         vhost_dev_cleanup(dev, true);
 
+        /* Restore memory to default empty mapping. */
         memory->nregions = 0;
         RCU_INIT_POINTER(dev->memory, memory);
-        return 0;
 }
 
 void vhost_dev_stop(struct vhost_dev *dev)