Hello! On Sun 28-03-21 17:11:43, lyl2019@xxxxxxxxxxxxxxxx wrote: > My static analyzer tool reported a use after free in fsnotify_put_mark_wake > of the file: fs/notify/mark.c. > > In fsnotify_put_mark_wake, it calls fsnotify_put_mark(mark). Inside the function > fsnotify_put_mark(), if conn is NULL, it will call fsnotify_final_mark_destroy(mark) > to free mark->group by fsnotify_put_group(group) and return. I also had inspected > the implementation of fsnotify_put_group() and found that there is no cleanup operation > about group->user_waits. > > But after fsnotify_put_mark_wake() returned, mark->group is still used by > if (atomic_dec_and_test(&group->user_waits) && group->shutdown) and later. > > Is this an issue? I don't think this scenario is possible. fsnotify_put_mark_wake() can be called only for marks attached to objects and these have mark->conn != NULL and we are sure that fsnotify_destroy_group() will wait for all such marks to be torn down and freed before dropping last group reference and freeing the group. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
