> -----原始邮件----- > 发件人: "Jan Kara" <jack@xxxxxxx> > 发送时间: 2021-03-29 21:57:40 (星期一) > 收件人: lyl2019@xxxxxxxxxxxxxxxx > 抄送: jack@xxxxxxx, amir73il@xxxxxxxxx, linux-fsdevel@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx > 主题: Re: [BUG] fs/notify/mark: A potential use after free in fsnotify_put_mark_wake > > 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 Ok, thanks for your answer.
