From b027e2298bd588d6fa36ed2eda97447fb3eac078 Mon Sep 17 00:00:00 2001 From: Gaurav Kohli Date: Tue, 23 Jan 2018 13:16:34 +0530 Subject: tty: fix data race between tty_init_dev and flush of buf There can be a race, if receive_buf call comes before tty initialization completes in n_tty_open and tty->disc_data may be NULL. CPU0 CPU1 ---- ---- 000|n_tty_receive_buf_common() n_tty_open() -001|n_tty_receive_buf2() tty_ldisc_open.isra.3() -002|tty_ldisc_receive_buf(inline) tty_ldisc_setup() Using ldisc semaphore lock in tty_init_dev till disc_data initializes completely. Signed-off-by: Gaurav Kohli Reviewed-by: Alan Cox Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_ldisc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/tty/tty_ldisc.c') diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index 24ec5c7e6b20..4e7946c0484b 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -337,7 +337,7 @@ static inline void __tty_ldisc_unlock(struct tty_struct *tty) ldsem_up_write(&tty->ldisc_sem); } -static int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) +int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) { int ret; @@ -348,7 +348,7 @@ static int tty_ldisc_lock(struct tty_struct *tty, unsigned long timeout) return 0; } -static void tty_ldisc_unlock(struct tty_struct *tty) +void tty_ldisc_unlock(struct tty_struct *tty) { clear_bit(TTY_LDISC_HALTED, &tty->flags); __tty_ldisc_unlock(tty); -- cgit v1.2.3