From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0FD771C862F; Tue, 30 Sep 2025 15:22:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759245736; cv=none; b=lMPBPOpTtwHHjdP1YQ4Ianfa/s+hpjTZ3mD9zNwehOoV4UCs7yNAwOT71QVao6lM5qqYMIzLlJoEJipOQ8KEhhq96TRnxBncoaa0awX05LGYlblnIKnfMs4CJhD/4rdftZlEcYg+Yu6o9yFKpdePhrxU2UPhAmk5Pyo4f3wOAAI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759245736; c=relaxed/simple; bh=7VblKmalQnyOa/sBgnHlwI3cVoby93lRW3Kl7zNyY1c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=REKwT/0HrKiX9WhHCcvUVJ/khNw+Ckts1j+IeS+EEb0H18v1akpBIbWo/i7hy26qq1e1ITjR9+Oz0NZJhOG3vZf3ZiFGUahaZv3pSvBCS3OZGBpd1oNrSv2L7xjPDkTcd565GX07z4o3Nl4OzwsSnlfJgTz+76JsYKGy3Ui4HAQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=a2USlke9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="a2USlke9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6EE0DC4CEF0; Tue, 30 Sep 2025 15:22:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1759245735; bh=7VblKmalQnyOa/sBgnHlwI3cVoby93lRW3Kl7zNyY1c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=a2USlke9sb3KCxV1YihiVw7rpePfO8pEiHGRzwgPY/j6QH7P6NMGziWYhGX1aNCQp tKdwKftQd2owQHm1MMsrrmIGT/Oj99VZ619aGMImO8aBZZuEELITi7l1F+opq14FQE 3N5EJkG/Nig5bsNLelKnOR7cvHPdFsDn7rdNH8RA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vincent Mailhol , Marc Kleine-Budde , Sasha Levin Subject: [PATCH 6.6 35/91] can: etas_es58x: populate ndo_change_mtu() to prevent buffer overflow Date: Tue, 30 Sep 2025 16:47:34 +0200 Message-ID: <20250930143822.613921721@linuxfoundation.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20250930143821.118938523@linuxfoundation.org> References: <20250930143821.118938523@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vincent Mailhol [ Upstream commit 38c0abad45b190a30d8284a37264d2127a6ec303 ] Sending an PF_PACKET allows to bypass the CAN framework logic and to directly reach the xmit() function of a CAN driver. The only check which is performed by the PF_PACKET framework is to make sure that skb->len fits the interface's MTU. Unfortunately, because the etas_es58x driver does not populate its net_device_ops->ndo_change_mtu(), it is possible for an attacker to configure an invalid MTU by doing, for example: $ ip link set can0 mtu 9999 After doing so, the attacker could open a PF_PACKET socket using the ETH_P_CANXL protocol: socket(PF_PACKET, SOCK_RAW, htons(ETH_P_CANXL)); to inject a malicious CAN XL frames. For example: struct canxl_frame frame = { .flags = 0xff, .len = 2048, }; The CAN drivers' xmit() function are calling can_dev_dropped_skb() to check that the skb is valid, unfortunately under above conditions, the malicious packet is able to go through can_dev_dropped_skb() checks: 1. the skb->protocol is set to ETH_P_CANXL which is valid (the function does not check the actual device capabilities). 2. the length is a valid CAN XL length. And so, es58x_start_xmit() receives a CAN XL frame which it is not able to correctly handle and will thus misinterpret it as a CAN(FD) frame. This can result in a buffer overflow. For example, using the es581.4 variant, the frame will be dispatched to es581_4_tx_can_msg(), go through the last check at the beginning of this function: if (can_is_canfd_skb(skb)) return -EMSGSIZE; and reach this line: memcpy(tx_can_msg->data, cf->data, cf->len); Here, cf->len corresponds to the flags field of the CAN XL frame. In our previous example, we set canxl_frame->flags to 0xff. Because the maximum expected length is 8, a buffer overflow of 247 bytes occurs! Populate net_device_ops->ndo_change_mtu() to ensure that the interface's MTU can not be set to anything bigger than CAN_MTU or CANFD_MTU (depending on the device capabilities). By fixing the root cause, this prevents the buffer overflow. Fixes: 8537257874e9 ("can: etas_es58x: add core support for ETAS ES58X CAN USB interfaces") Signed-off-by: Vincent Mailhol Link: https://patch.msgid.link/20250918-can-fix-mtu-v1-1-0d1cada9393b@kernel.org Signed-off-by: Marc Kleine-Budde Signed-off-by: Sasha Levin --- drivers/net/can/usb/etas_es58x/es58x_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/can/usb/etas_es58x/es58x_core.c b/drivers/net/can/usb/etas_es58x/es58x_core.c index 5e3a72b7c4691..bb49a2c0a9a5c 100644 --- a/drivers/net/can/usb/etas_es58x/es58x_core.c +++ b/drivers/net/can/usb/etas_es58x/es58x_core.c @@ -7,7 +7,7 @@ * * Copyright (c) 2019 Robert Bosch Engineering and Business Solutions. All rights reserved. * Copyright (c) 2020 ETAS K.K.. All rights reserved. - * Copyright (c) 2020-2022 Vincent Mailhol + * Copyright (c) 2020-2025 Vincent Mailhol */ #include @@ -1977,6 +1977,7 @@ static const struct net_device_ops es58x_netdev_ops = { .ndo_stop = es58x_stop, .ndo_start_xmit = es58x_start_xmit, .ndo_eth_ioctl = can_eth_ioctl_hwts, + .ndo_change_mtu = can_change_mtu, }; static const struct ethtool_ops es58x_ethtool_ops = { -- 2.51.0