[PATCH 4.4 12/64] can: peak_usb: add range checking in decode operations

Greg Kroah-Hartman
2020-11-17T13:06:32Z

From: Dan Carpenter <dan.carpenter@oracle.com>

[ Upstream commit a6921dd524fe31d1f460c161d3526a407533b6db ]

These values come from skb->data so Smatch considers them untrusted. I
believe Smatch is correct but I don't have a way to test this.

The usb_if->dev[] array has 2 elements but the index is in the 0-15
range without checks. The cfd->len can be up to 255 but the maximum
valid size is CANFD_MAX_DLEN (64) so that could lead to memory
corruption.

Fixes: 0a25e1f4f185 ("can: peak_usb: add support for PEAK new CANFD USB adapters")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20200813140604.GA456946@mwanda
Acked-by: Stephane Grosjean <s.grosjean@peak-system.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/can/usb/peak_usb/pcan_usb_fd.c | 48 +++++++++++++++++-----
1 file changed, 37 insertions(+), 11 deletions(-)

diff --git a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
index 1b75d5304a2c1..2e62cdc7ec7ab 100644
--- a/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
+++ b/drivers/net/can/usb/peak_usb/pcan_usb_fd.c
@@ -475,12 +475,18 @@ static int pcan_usb_fd_decode_canmsg(struct pcan_usb_fd_if *usb_if,
struct pucan_msg *rx_msg)
{
struct pucan_rx_msg *rm = (struct pucan_rx_msg *)rx_msg;
- struct peak_usb_device *dev = usb_if->dev[pucan_msg_get_channel(rm)];
- struct net_device *netdev = dev->netdev;
+ struct peak_usb_device *dev;
+ struct net_device *netdev;
struct canfd_frame *cfd;
struct sk_buff *skb;
const u16 rx_msg_flags = le16_to_cpu(rm->flags);

+ if (pucan_msg_get_channel(rm) >= ARRAY_SIZE(usb_if->dev))
+ return -ENOMEM;
+
+ dev = usb_if->dev[pucan_msg_get_channel(rm)];
+ netdev = dev->netdev;
+
if (rx_msg_flags & PUCAN_MSG_EXT_DATA_LEN) {
/* CANFD frame case */
skb = alloc_canfd_skb(netdev, &cfd);
@@ -527,15 +533,21 @@ static int pcan_usb_fd_decode_status(struct pcan_usb_fd_if *usb_if,
struct pucan_msg *rx_msg)
{
struct pucan_status_msg *sm = (struct pucan_status_msg *)rx_msg;
- struct peak_usb_device *dev = usb_if->dev[pucan_stmsg_get_channel(sm)];
- struct pcan_usb_fd_device *pdev =
- container_of(dev, struct pcan_usb_fd_device, dev);
+ struct pcan_usb_fd_device *pdev;
enum can_state new_state = CAN_STATE_ERROR_ACTIVE;
enum can_state rx_state, tx_state;
- struct net_device *netdev = dev->netdev;
+ struct peak_usb_device *dev;
+ struct net_device *netdev;
struct can_frame *cf;
struct sk_buff *skb;

+ if (pucan_stmsg_get_channel(sm) >= ARRAY_SIZE(usb_if->dev))
+ return -ENOMEM;
+
+ dev = usb_if->dev[pucan_stmsg_get_channel(sm)];
+ pdev = container_of(dev, struct pcan_usb_fd_device, dev);
+ netdev = dev->netdev;
+
/* nothing should be sent while in BUS_OFF state */
if (dev->can.state == CAN_STATE_BUS_OFF)
return 0;
@@ -588,9 +600,14 @@ static int pcan_usb_fd_decode_error(struct pcan_usb_fd_if *usb_if,
struct pucan_msg *rx_msg)
{
struct pucan_error_msg *er = (struct pucan_error_msg *)rx_msg;
- struct peak_usb_device *dev = usb_if->dev[pucan_ermsg_get_channel(er)];
- struct pcan_usb_fd_device *pdev =
- container_of(dev, struct pcan_usb_fd_device, dev);
+ struct pcan_usb_fd_device *pdev;
+ struct peak_usb_device *dev;
+
+ if (pucan_ermsg_get_channel(er) >= ARRAY_SIZE(usb_if->dev))
+ return -EINVAL;
+
+ dev = usb_if->dev[pucan_ermsg_get_channel(er)];
+ pdev = container_of(dev, struct pcan_usb_fd_device, dev);

/* keep a trace of tx and rx error counters for later use */
pdev->bec.txerr = er->tx_err_cnt;
@@ -604,11 +621,17 @@ static int pcan_usb_fd_decode_overrun(struct pcan_usb_fd_if *usb_if,
struct pucan_msg *rx_msg)
{
struct pcan_ufd_ovr_msg *ov = (struct pcan_ufd_ovr_msg *)rx_msg;
- struct peak_usb_device *dev = usb_if->dev[pufd_omsg_get_channel(ov)];
- struct net_device *netdev = dev->netdev;
+ struct peak_usb_device *dev;
+ struct net_device *netdev;
struct can_frame *cf;
struct sk_buff *skb;

+ if (pufd_omsg_get_channel(ov) >= ARRAY_SIZE(usb_if->dev))
+ return -EINVAL;
+
+ dev = usb_if->dev[pufd_omsg_get_channel(ov)];
+ netdev = dev->netdev;
+
/* allocate an skb to store the error frame */
skb = alloc_can_err_skb(netdev, &cf);
if (!skb)
@@ -726,6 +749,9 @@ static int pcan_usb_fd_encode_msg(struct peak_usb_device *dev,
u16 tx_msg_size, tx_msg_flags;
u8 can_dlc;

+ if (cfd->len > CANFD_MAX_DLEN)
+ return -EINVAL;
+
tx_msg_size = ALIGN(sizeof(struct pucan_tx_msg) + cfd->len, 4);
tx_msg->size = cpu_to_le16(tx_msg_size);
tx_msg->type = cpu_to_le16(PUCAN_MSG_CAN_TX);
--
2.27.0