smatch stuff: returning signed values in nfs_negotiate_security()

[Dan Carpenter <error27@gmail.com>]

Hi Brian,

7ebb931598 "NFS: use secinfo when crossing mountpoints" has a signed vs
unsigned bug.

fs/nfs/namespace.c +189 nfs_lookup_with_sec(10)
	warn: unsigned 'flavor' is never less than zero.

   161                  page = alloc_page(GFP_KERNEL);
   162                  if (!page) {
   163                          status = -ENOMEM;
				^^^^^^^^^^^^^^^^
	Btw. this gets over written after we goto out.

   164                          goto out;
   165                  }
   166                  flavors = page_address(page);
   167                  status = secinfo(parent->d_inode, &dentry->d_name, flavors);
   168                  flavor = nfs_find_best_sec(flavors, dentry->d_inode);
   169                  put_page(page);
   170          }
   171
   172          return flavor;
   173
   174  out:
   175          status = -ENOMEM;
		^^^^^^^^^^^^^^^^
	Here.

More importantly, the caller is expecting an unsigned return value.  The
check for negative returns in nfs_lookup_with_sec() doesn't work.

   176          return status;

regards,
dan carpenter