Messages in this thread | | | Date | Mon, 29 Aug 2022 09:10:03 +0200 | Subject | Re: [PATCH] tty: n_gsm: initialize more members at gsm_alloc_mux() | From | Jiri Slaby <> |
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On 27. 08. 22, 15:47, Tetsuo Handa wrote: > syzbot is reporting use of uninitialized spinlock at gsmld_write() [1], for > commit 32dd59f96924f45e ("tty: n_gsm: fix race condition in gsmld_write()") > allows accessing gsm->tx_lock before gsm_activate_mux() initializes it. > > Since object initialization should be done right after allocation in order > to avoid accessing uninitialized memory, move initialization of > timer/work/waitqueue/spinlock from gsmld_open()/gsm_activate_mux() to > gsm_alloc_mux().
LGTM, I wonder why this was not like this forever.
Acked-by: Jiri Slaby <jirislaby@kernel.org>
> Link: https://syzkaller.appspot.com/bug?extid=cf155def4e717db68a12 [1] > Reported-by: syzbot <syzbot+cf155def4e717db68a12@syzkaller.appspotmail.com> > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Tested-by: syzbot <syzbot+cf155def4e717db68a12@syzkaller.appspotmail.com> > Fixes: 32dd59f96924f45e ("tty: n_gsm: fix race condition in gsmld_write()") > --- > drivers/tty/n_gsm.c | 17 ++++++----------- > 1 file changed, 6 insertions(+), 11 deletions(-) > > diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c > index caa5c14ed57f..70cd90474679 100644 > --- a/drivers/tty/n_gsm.c > +++ b/drivers/tty/n_gsm.c > @@ -2501,13 +2501,6 @@ static int gsm_activate_mux(struct gsm_mux *gsm) > if (dlci == NULL) > return -ENOMEM; > > - timer_setup(&gsm->kick_timer, gsm_kick_timer, 0); > - timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0); > - INIT_WORK(&gsm->tx_work, gsmld_write_task); > - init_waitqueue_head(&gsm->event); > - spin_lock_init(&gsm->control_lock); > - spin_lock_init(&gsm->tx_lock); > - > if (gsm->encoding == 0) > gsm->receive = gsm0_receive; > else > @@ -2612,6 +2605,12 @@ static struct gsm_mux *gsm_alloc_mux(void) > kref_init(&gsm->ref); > INIT_LIST_HEAD(&gsm->tx_ctrl_list); > INIT_LIST_HEAD(&gsm->tx_data_list); > + timer_setup(&gsm->kick_timer, gsm_kick_timer, 0); > + timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0); > + INIT_WORK(&gsm->tx_work, gsmld_write_task); > + init_waitqueue_head(&gsm->event); > + spin_lock_init(&gsm->control_lock); > + spin_lock_init(&gsm->tx_lock); > > gsm->t1 = T1; > gsm->t2 = T2; > @@ -2946,10 +2945,6 @@ static int gsmld_open(struct tty_struct *tty) > > gsmld_attach_gsm(tty, gsm); > > - timer_setup(&gsm->kick_timer, gsm_kick_timer, 0); > - timer_setup(&gsm->t2_timer, gsm_control_retransmit, 0); > - INIT_WORK(&gsm->tx_work, gsmld_write_task); > - > return 0; > } >
-- js suse labs
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