On Fri, Nov 20, 2020 at 05:14:26PM -0600, Eric W. Biederman wrote: > /* > * Check whether the specified fd has an open file. > */ > -#define fcheck(fd) fcheck_files(current->files, fd) > +#define fcheck(fd) files_lookup_fd_rcu(current->files, fd) Huh? fs/file.c:1113: file = fcheck(oldfd); dup3(), under ->file_lock, no rcu_read_lock() in sight fs/locks.c:2548: f = fcheck(fd); fcntl_setlk(), ditto fs/locks.c:2679: f = fcheck(fd); fcntl_setlk64(), ditto fs/notify/dnotify/dnotify.c:330: f = fcheck(fd); fcntl_dirnotify(); this one _is_ under rcu_read_lock(). IOW, unless I've missed something earlier in the series, this is wrong.
