mmap: check ->vm_ops before dereferencing

Check whether the VMA has a vm_ops before calling close, just
like we check vm_ops before calling open a few dozen lines
higher up in the function.

Signed-off-by: Rik van Riel <[e-mail]>
Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

mm/mmap.c

···
 		return 0;
 
 	/* Clean everything up if vma_adjust failed. */
-	new->vm_ops->close(new);
+	if (new->vm_ops && new->vm_ops->close)
+		new->vm_ops->close(new);
 	if (new->vm_file) {
 		if (vma->vm_flags & VM_EXECUTABLE)
 			removed_exe_file_vma(mm);