can: ems_usb: fix memory leak

commit 9969e3c5f40c166e3396acc36c34f9de502929f6 upstream.

In ems_usb_start() MAX_RX_URBS coherent buffers are allocated and
there is nothing, that frees them:

1) In callback function the urb is resubmitted and that's all
2) In disconnect function urbs are simply killed, but URB_FREE_BUFFER
   is not set (see ems_usb_start) and this flag cannot be used with
   coherent buffers.

So, all allocated buffers should be freed with usb_free_coherent()
explicitly.

Side note: This code looks like a copy-paste of other can drivers. The
same patch was applied to mcba_usb driver and it works nice with real
hardware. There is no change in functionality, only clean-up code for
coherent buffers.

Fixes: 702171adeed3 ("ems_usb: Added support for EMS CPC-USB/ARM7 CAN/USB interface")
Link: https://lore.kernel.org/r/59aa9fbc9a8cbf9af2bbd2f61a659c480b415800.1627404470.git.paskripkin@gmail.com
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/can/usb/ems_usb.c b/drivers/net/can/usb/ems_usb.c
index 022a9b3c7d4e8562eb88e4980b81ed5ab1f62da1..d62d61d734ea1cb1c225e58acef1134e906fcd07 100644 (file)
--- a/drivers/net/can/usb/ems_usb.c
+++ b/drivers/net/can/usb/ems_usb.c
@@ -267,6 +267,8 @@ struct ems_usb {
        unsigned int free_slots; /* remember number of available slots */
 
        struct ems_cpc_msg active_params; /* active controller parameters */
+       void *rxbuf[MAX_RX_URBS];
+       dma_addr_t rxbuf_dma[MAX_RX_URBS];
 };
 
 static void ems_usb_read_interrupt_callback(struct urb *urb)
@@ -598,6 +600,7 @@ static int ems_usb_start(struct ems_usb *dev)
        for (i = 0; i < MAX_RX_URBS; i++) {
                struct urb *urb = NULL;
                u8 *buf = NULL;
+               dma_addr_t buf_dma;
 
                /* create a URB, and a buffer for it */
                urb = usb_alloc_urb(0, GFP_KERNEL);
@@ -607,7 +610,7 @@ static int ems_usb_start(struct ems_usb *dev)
                }
 
                buf = usb_alloc_coherent(dev->udev, RX_BUFFER_SIZE, GFP_KERNEL,
-                                        &urb->transfer_dma);
+                                        &buf_dma);
                if (!buf) {
                        netdev_err(netdev, "No memory left for USB buffer\n");
                        usb_free_urb(urb);
@@ -615,6 +618,8 @@ static int ems_usb_start(struct ems_usb *dev)
                        break;
                }
 
+               urb->transfer_dma = buf_dma;
+
                usb_fill_bulk_urb(urb, dev->udev, usb_rcvbulkpipe(dev->udev, 2),
                                  buf, RX_BUFFER_SIZE,
                                  ems_usb_read_bulk_callback, dev);
@@ -630,6 +635,9 @@ static int ems_usb_start(struct ems_usb *dev)
                        break;
                }
 
+               dev->rxbuf[i] = buf;
+               dev->rxbuf_dma[i] = buf_dma;
+
                /* Drop reference, USB core will take care of freeing it */
                usb_free_urb(urb);
        }
@@ -695,6 +703,10 @@ static void unlink_all_urbs(struct ems_usb *dev)
 
        usb_kill_anchored_urbs(&dev->rx_submitted);
 
+       for (i = 0; i < MAX_RX_URBS; ++i)
+               usb_free_coherent(dev->udev, RX_BUFFER_SIZE,
+                                 dev->rxbuf[i], dev->rxbuf_dma[i]);
+
        usb_kill_anchored_urbs(&dev->tx_submitted);
        atomic_set(&dev->active_tx_urbs, 0);