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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Jia-Ju Bai <baijiaju1990@gmail.com>,
	"David S . Miller" <davem@davemloft.net>,
	Sasha Levin <sashal@kernel.org>,
	netdev@vger.kernel.org
Subject: [PATCH AUTOSEL 4.9 16/21] isdn: i4l: isdn_tty: Fix some concurrency double-free bugs
Date: Tue, 12 Feb 2019 21:40:35 -0500	[thread overview]
Message-ID: <20190213024040.21740-16-sashal@kernel.org> (raw)
In-Reply-To: <20190213024040.21740-1-sashal@kernel.org>

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ 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>
---
 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


  parent reply	other threads:[~2019-02-13  2:45 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20190213024040.21740-1-sashal@kernel.org>
2019-02-13  2:40 ` [PATCH AUTOSEL 4.9 09/21] qed: Fix qed_ll2_post_rx_buffer_notify_fw() by adding a write memory barrier Sasha Levin
2019-02-13  2:40 ` [PATCH AUTOSEL 4.9 10/21] net: hns: Fix use after free identified by SLUB debug Sasha Levin
2019-02-13  2:40 ` [PATCH AUTOSEL 4.9 15/21] net: stmmac: Fix PCI module removal leak Sasha Levin
2019-02-13  2:40 ` Sasha Levin [this message]
2019-02-13  2:40 ` [PATCH AUTOSEL 4.9 17/21] atm: he: fix sign-extension overflow on large shift Sasha Levin
2019-02-13  2:40 ` [PATCH AUTOSEL 4.9 19/21] mlxsw: spectrum_switchdev: Do not treat static FDB entries as sticky Sasha Levin
2019-02-13  2:40 ` [PATCH AUTOSEL 4.9 20/21] net/mlx5e: Fix wrong (zero) TX drop counter indication for representor Sasha Levin
2019-02-13  2:40 ` [PATCH AUTOSEL 4.9 21/21] isdn: avm: Fix string plus integer warning from Clang Sasha Levin

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