diff options
| author | Jia-Ju Bai <baijiaju1990@gmail.com> | 2019-01-08 16:04:48 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-27 12:08:55 +0300 |
| commit | 3dd0ce706e0bcec806a68adf9598b7c31405e03e (patch) | |
| tree | 142a6bbe60d3e81317bbb7007195bb6dd5677a55 | |
| parent | 1b8742ba98a5bf0b5d0e30fb61cbe1c61fa4e88b (diff) | |
| download | linux-3dd0ce706e0bcec806a68adf9598b7c31405e03e.tar.xz | |
isdn: i4l: isdn_tty: Fix some concurrency double-free bugs
[ 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@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/isdn/i4l/isdn_tty.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/isdn/i4l/isdn_tty.c b/drivers/isdn/i4l/isdn_tty.c index b730037a0e2d..9cff667b2d24 100644 --- a/drivers/isdn/i4l/isdn_tty.c +++ b/drivers/isdn/i4l/isdn_tty.c @@ -1456,15 +1456,19 @@ 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); } /* |