Re: [syzbot] KASAN: use-after-free Read in rxe_queue_cleanup

[Zhu Yanjun]

On Sun, Nov 21, 2021 at 10:16 PM Leon Romanovsky <leon@xxxxxxxxxx> wrote:
>
> On Sat, Nov 20, 2021 at 06:02:02PM +0300, Pavel Skripkin wrote:
> > On 11/19/21 12:27, syzbot wrote:
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit:    8d0112ac6fd0 Merge tag 'net-5.16-rc2' of git://git.kernel...
> > > git tree:       net
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=14e3eeaab00000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=6d3b8fd1977c1e73
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=aab53008a5adf26abe91
> > > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> > >
> > > Unfortunately, I don't have any reproducer for this issue yet.
> > >
> > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > Reported-by: syzbot+aab53008a5adf26abe91@xxxxxxxxxxxxxxxxxxxxxxxxx
> > >
> > > Free swap  = 0kB
> > > Total swap = 0kB
> > > 2097051 pages RAM
> > > 0 pages HighMem/MovableOnly
> > > 384517 pages reserved
> > > 0 pages cma reserved
> > > ==================================================================
> > > BUG: KASAN: use-after-free in rxe_queue_cleanup+0xf4/0x100 drivers/infiniband/sw/rxe/rxe_queue.c:193
> > > Read of size 8 at addr ffff88814a6b6e90 by task syz-executor.3/9534
> > >
> >
> > On error handling path in rxe_qp_from_init() qp->sq.queue is freed and then
> > rxe_create_qp() will drop last reference to this object. qp clean up
> > function will try to free this queue one time and it causes UAF bug.
> >
> > Just for thoughts.
Agree with you. Thanks a lot.

Zhu Yanjun
>
> You are right, can you please submit patch?
>
> Thanks
>
> >
> >
> > diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c
> > b/drivers/infiniband/sw/rxe/rxe_qp.c
> > index 975321812c87..54b8711321c1 100644
> > --- a/drivers/infiniband/sw/rxe/rxe_qp.c
> > +++ b/drivers/infiniband/sw/rxe/rxe_qp.c
> > @@ -359,6 +359,7 @@ int rxe_qp_from_init(struct rxe_dev *rxe, struct rxe_qp
> > *qp, struct rxe_pd *pd,
> >
> >  err2:
> >       rxe_queue_cleanup(qp->sq.queue);
> > +     qp->sq.queue = NULL;
> >  err1:
> >       qp->pd = NULL;
> >       qp->rcq = NULL;
> >
> >
> >
> >
> >
> > With regards,
> > Pavel Skripkin