From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
[ Upstream commit 2ff33d6637393fe9348357285931811b76e1402f ]
The functions isdn_tty_tiocmset() and isdn_tty_set_termios() may be
concurrently executed.
isdn_tty_tiocmset
isdn_tty_modem_hup
line 719: kfree(info->dtmf_state);
line 721: kfree(info->silence_state);
line 723: kfree(info->adpcms);
line 725: kfree(info->adpcmr);
isdn_tty_set_termios
isdn_tty_modem_hup
line 719: kfree(info->dtmf_state);
line 721: kfree(info->silence_state);
line 723: kfree(info->adpcms);
line 725: kfree(info->adpcmr);
Thus, some concurrency double-free bugs may occur.
These possible bugs are found by a static tool written by myself and
my manual code review.
To fix these possible bugs, the mutex lock "modem_info_mutex" used in
isdn_tty_tiocmset() is added in isdn_tty_set_termios().
Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/isdn/i4l/isdn_tty.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/isdn/i4l/isdn_tty.c b/drivers/isdn/i4l/isdn_tty.c
index 63eaa0a9f8a1..d4e0d1602c80 100644
--- a/drivers/isdn/i4l/isdn_tty.c
+++ b/drivers/isdn/i4l/isdn_tty.c
@@ -1455,15 +1455,19 @@ isdn_tty_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
modem_info *info = (modem_info *) tty->driver_data;
+ mutex_lock(&modem_info_mutex);
if (!old_termios)
isdn_tty_change_speed(info);
else {
if (tty->termios.c_cflag == old_termios->c_cflag &&
tty->termios.c_ispeed == old_termios->c_ispeed &&
- tty->termios.c_ospeed == old_termios->c_ospeed)
+ tty->termios.c_ospeed == old_termios->c_ospeed) {
+ mutex_unlock(&modem_info_mutex);
return;
+ }
isdn_tty_change_speed(info);
}
+ mutex_unlock(&modem_info_mutex);
}
/*
--
2.19.1
