From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3A3573D3488; Wed, 20 May 2026 10:15:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779272102; cv=none; b=faiYCGd/XBnQrMeA0krc51tEPLJhPNfu8vCSTp12bQ9U4bMSlezAzOguQsoTkyjXt1eWo5hFErDz+CpwKZxNjEtL09j9KkKLFPAY0WoOV02xyVBNg3mWbEVkINrJPkFCYI/mcyZs8TQ1iM4J7dogPFxEbY9iivuppRcb/+1HB3w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779272102; c=relaxed/simple; bh=8wFPq94yFSybvgXDcni+KLTML8MIhHDChwtg6j+50AM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=H8eZgggtyXmkpRJ+B4frx/Kl4ptpOMARe929a4bQLNrNXaGLiA/DTkduf6qourJHBlBODa4puMeub8OULIYPXFT2deiFkXG4VONBZLsd7eUMZOJyB2m3HqWAlHZC/yHpRAll18FKzagBPKYz1SxA31Zt2zKkccmCiO4JtMkZGik= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=AogE4ric; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="AogE4ric" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E0A541F000E9; Wed, 20 May 2026 10:15:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1779272100; bh=bn0l51DDioA8sZuJfYzycRmVprKeKfbJ4kO44tV877o=; h=From:To:Cc:Subject:Date; b=AogE4ricj/CApjPIj0bjsa4bS2dYCFqsBP4Qq8Z6dqur0H7KHCADBihKZ9gdTwtuu E49uM1BYv1CTT05PfGYItvbF7iYrgj6rS1p8XRj3q9EcgQtalk/F5Pr96OXWtBlje+ EmC2eS12i7gf5iqubdvwEIBrw0kBmCN0TCjITj9zzxEdBF9YqJiDmbXdx89dhesPuw OcETxRFV1Kw98KKBQTHsW6Vs8uMU0uYX0x0crVX3eXB/dD2KDojLW3ui68W+2QvkLK 4A8vMllOE2p2TjZhOKFK6jujSNQxwEWRI7FRDu0lk+8Zb60x9ka3MycnUjGpDge/cF 37nDzHOhgcG1Q== Received: from johan by xi.lan with local (Exim 4.98.2) (envelope-from ) id 1wPdx4-00000002l5S-30P0; Wed, 20 May 2026 12:14:58 +0200 From: Johan Hovold To: Johan Hovold Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH] USB: serial: mct_u232: fix memory corruption with small endpoint Date: Wed, 20 May 2026 12:14:52 +0200 Message-ID: <20260520101452.657643-1-johan@kernel.org> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The driver overrides the maximum transfer size for a specific device which only accepts 16 byte packets for its 32 byte bulk-out endpoint. Make sure to never increase the maximum transfer size to prevent slab corruption should a malicious device report a smaller endpoint max packet size than expected. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold --- drivers/usb/serial/mct_u232.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c index 18844b92bd08..ca1530da6e77 100644 --- a/drivers/usb/serial/mct_u232.c +++ b/drivers/usb/serial/mct_u232.c @@ -378,6 +378,7 @@ static int mct_u232_port_probe(struct usb_serial_port *port) { struct usb_serial *serial = port->serial; struct mct_u232_private *priv; + u16 pid; /* check first to simplify error handling */ if (!serial->port[1] || !serial->port[1]->interrupt_in_urb) { @@ -385,6 +386,16 @@ static int mct_u232_port_probe(struct usb_serial_port *port) return -ENODEV; } + /* + * Compensate for a hardware bug: although the Sitecom U232-P25 + * device reports a maximum output packet size of 32 bytes, + * it seems to be able to accept only 16 bytes (and that's what + * SniffUSB says too...) + */ + pid = le16_to_cpu(serial->dev->descriptor.idProduct); + if (pid == MCT_U232_SITECOM_PID) + port->bulk_out_size = min(16, port->bulk_out_size); + priv = kzalloc_obj(*priv); if (!priv) return -ENOMEM; @@ -410,7 +421,6 @@ static void mct_u232_port_remove(struct usb_serial_port *port) static int mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port) { - struct usb_serial *serial = port->serial; struct mct_u232_private *priv = usb_get_serial_port_data(port); int retval = 0; unsigned int control_state; @@ -418,15 +428,6 @@ static int mct_u232_open(struct tty_struct *tty, struct usb_serial_port *port) unsigned char last_lcr; unsigned char last_msr; - /* Compensate for a hardware bug: although the Sitecom U232-P25 - * device reports a maximum output packet size of 32 bytes, - * it seems to be able to accept only 16 bytes (and that's what - * SniffUSB says too...) - */ - if (le16_to_cpu(serial->dev->descriptor.idProduct) - == MCT_U232_SITECOM_PID) - port->bulk_out_size = 16; - /* Do a defined restart: the normal serial device seems to * always turn on DTR and RTS here, so do the same. I'm not * sure if this is really necessary. But it should not harm -- 2.53.0