From 1cf469026d4a2308eaa91d04dca4a900d07a5c2e Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 23 Feb 2026 17:51:17 +0100 Subject: [PATCH] can: ems_usb: ems_usb_read_bulk_callback(): check the proper length of a message commit 38a01c9700b0dcafe97dfa9dc7531bf4a245deff upstream. When looking at the data in a USB urb, the actual_length is the size of the buffer passed to the driver, not the transfer_buffer_length which is set by the driver as the max size of the buffer. When parsing the messages in ems_usb_read_bulk_callback() properly check the size both at the beginning of parsing the message to make sure it is big enough for the expected structure, and at the end of the message to make sure we don't overflow past the end of the buffer for the next message. Cc: Vincent Mailhol Cc: Marc Kleine-Budde Cc: stable@kernel.org Assisted-by: gkh_clanker_2000 Signed-off-by: Greg Kroah-Hartman Link: https://patch.msgid.link/2026022316-answering-strainer-a5db@gregkh Fixes: 702171adeed3 ("ems_usb: Added support for EMS CPC-USB/ARM7 CAN/USB interface") Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- drivers/net/can/usb/ems_usb.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c index fac8ac79df59..d8c881130e90 100644 --- a/drivers/net/can/usb/ems_usb.c +++ b/drivers/net/can/usb/ems_usb.c @@ -445,6 +445,11 @@ static void ems_usb_read_bulk_callback(struct urb *urb) start = CPC_HEADER_SIZE; while (msg_count) { + if (start + CPC_MSG_HEADER_LEN > urb->actual_length) { + netdev_err(netdev, "format error\n"); + break; + } + msg = (struct ems_cpc_msg *)&ibuf[start]; switch (msg->type) { @@ -474,7 +479,7 @@ static void ems_usb_read_bulk_callback(struct urb *urb) start += CPC_MSG_HEADER_LEN + msg->length; msg_count--; - if (start > urb->transfer_buffer_length) { + if (start > urb->actual_length) { netdev_err(netdev, "format error\n"); break; }