[bug report] ovl: copy up of disconnected dentries

[Dan Carpenter <dan.carpenter@oracle.com>]

Hello Amir Goldstein,

The patch aa3ff3c152ff: "ovl: copy up of disconnected dentries" from
Oct 15, 2017, leads to the following static checker warning:

	fs/overlayfs/copy_up.c:972 ovl_copy_up_flags()
	warn: 'old_cred' not released on lines: 944.

fs/overlayfs/copy_up.c
   932  static int ovl_copy_up_flags(struct dentry *dentry, int flags)
   933  {
   934          int err = 0;
   935          const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
   936          bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);
   937  
   938          /*
   939           * With NFS export, copy up can get called for a disconnected non-dir.
   940           * In this case, we will copy up lower inode to index dir without
   941           * linking it to upper dir.
   942           */
   943          if (WARN_ON(disconnected && d_is_dir(dentry)))
   944                  return -EIO;

Should this call revert_creds(old_cred); before returning?

   945  
   946          while (!err) {
   947                  struct dentry *next;
   948                  struct dentry *parent = NULL;
   949  
   950                  if (ovl_already_copied_up(dentry, flags))
   951                          break;
   952  
   953                  next = dget(dentry);
   954                  /* find the topmost dentry not yet copied up */
   955                  for (; !disconnected;) {
   956                          parent = dget_parent(next);
   957  
   958                          if (ovl_dentry_upper(parent))
   959                                  break;
   960  
   961                          dput(next);
   962                          next = parent;
   963                  }
   964  
   965                  err = ovl_copy_up_one(parent, next, flags);
   966  
   967                  dput(parent);
   968                  dput(next);
   969          }
   970          revert_creds(old_cred);
   971  
   972          return err;
   973  }

regards,
dan carpenter