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([106.39.42.118]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2e99a541cfbsm3257801a91.18.2024.11.07.03.35.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Nov 2024 03:35:42 -0800 (PST) From: Qiu-ji Chen To: johan@kernel.org, gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com, Qiu-ji Chen Subject: [PATCH v2] USB: serial: ftdi_sio: Fix atomicity violation in get_serial_info() Date: Thu, 7 Nov 2024 19:35:34 +0800 Message-Id: <20241107113534.402265-1-chenqiuji666@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Our static checker found a bug where set_serial_info() uses a mutex, but get_serial_info() does not. Fortunately, the impact of this is relatively minor. It doesn't cause a crash or any other serious issues. However, if a race condition occurs between set_serial_info() and get_serial_info(), there is a chance that the data returned by get_serial_info() will be inconsistent. Signed-off-by: Qiu-ji Chen Fixes: 3ae36bed3a93 ("fdti_sio: switch to ->[sg]et_serial()") --- Similar issues have been submitted or confirmed:=20 https://lore.kernel.org/all/20241002125845.785464707@linuxfoundation.org/=20 https://lore.kernel.org/all/20241106095819.15194-1-chenqiuji666@gmail.com/ --- V2: Revised the description, placed the reference link below "---". Used the correct patch prefix. Thanks Johan Hovold for helpful suggestion. --- drivers/usb/serial/ftdi_sio.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c index c6f17d732b95..e07c5e3eb18c 100644 --- a/drivers/usb/serial/ftdi_sio.c +++ b/drivers/usb/serial/ftdi_sio.c @@ -1443,9 +1443,11 @@ static void get_serial_info(struct tty_struct *tty, = struct serial_struct *ss) struct usb_serial_port *port =3D tty->driver_data; struct ftdi_private *priv =3D usb_get_serial_port_data(port); =20 + mutex_lock(&priv->cfg_lock); ss->flags =3D priv->flags; ss->baud_base =3D priv->baud_base; ss->custom_divisor =3D priv->custom_divisor; + mutex_unlock(&priv->cfg_lock); } =20 static int set_serial_info(struct tty_struct *tty, struct serial_struct *s= s) --=20 2.34.1