| Message ID | 20180719200607.30286-1-tomasbortoli@gmail.com |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
| Series | /net/9p/trans_fd.c: fix race-condition by flushing workqueue before the kfree() | expand |
On 2018/7/20 4:06, Tomas Bortoli wrote: > The patch adds the flush in p9_mux_poll_stop() as it the function used by > p9_conn_destroy(), in turn called by p9_fd_close() to stop the async > polling associated with the data regarding the connection. > > Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com> > Reported-by: syzbot+39749ed7d9ef6dfb23f6@syzkaller.appspotmail.com > --- > As shown by Syzbot, it is possible to provoke a race between p9_fd_close() > and p9_poll_workfn() that is called to take care of the async read/write work > to do. To make sure p9_fd_close() frees "trans" when it is not used anymore, > it has to explicitly call flush_scheduled_work() before the kfree(). > > net/9p/trans_fd.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c > index bf459ee0feab..76ae134c05d9 100644 > --- a/net/9p/trans_fd.c > +++ b/net/9p/trans_fd.c > @@ -185,6 +185,8 @@ static void p9_mux_poll_stop(struct p9_conn *m) > spin_lock_irqsave(&p9_poll_lock, flags); > list_del_init(&m->poll_pending_link); > spin_unlock_irqrestore(&p9_poll_lock, flags); > + > + flush_scheduled_work(); I suggest we should use flush_work(&p9_poll_work), flush_scheduled_work is not suitable. Thanks. > } > > /** >
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c index bf459ee0feab..76ae134c05d9 100644 --- a/net/9p/trans_fd.c +++ b/net/9p/trans_fd.c @@ -185,6 +185,8 @@ static void p9_mux_poll_stop(struct p9_conn *m) spin_lock_irqsave(&p9_poll_lock, flags); list_del_init(&m->poll_pending_link); spin_unlock_irqrestore(&p9_poll_lock, flags); + + flush_scheduled_work(); } /**
The patch adds the flush in p9_mux_poll_stop() as it the function used by p9_conn_destroy(), in turn called by p9_fd_close() to stop the async polling associated with the data regarding the connection. Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com> Reported-by: syzbot+39749ed7d9ef6dfb23f6@syzkaller.appspotmail.com --- As shown by Syzbot, it is possible to provoke a race between p9_fd_close() and p9_poll_workfn() that is called to take care of the async read/write work to do. To make sure p9_fd_close() frees "trans" when it is not used anymore, it has to explicitly call flush_scheduled_work() before the kfree(). net/9p/trans_fd.c | 2 ++ 1 file changed, 2 insertions(+)