Messages in this thread Patch in this message | | | Date | Sat, 27 Aug 2022 22:47:19 +0900 | Subject | [PATCH] tty: n_gsm: initialize more members at gsm_alloc_mux() | From | Tetsuo Handa <> |
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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().
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; } -- 2.34.1
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