From: Pavel Skripkin paskripkin@gmail.com
Syzbot reported memory leak in SocketCAN driver for Microchip CAN BUS Analyzer Tool. The problem was in unfreed usb_coherent.
In mcba_usb_start() 20 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 mcba_usb_start) and this flag cannot be used with coherent buffers.
Fail log: | [ 1354.053291][ T8413] mcba_usb 1-1:0.0 can0: device disconnected | [ 1367.059384][ T8420] kmemleak: 20 new suspected memory leaks (see /sys/kernel/debug/kmem)
So, all allocated buffers should be freed with usb_free_coherent() explicitly
NOTE: The same pattern for allocating and freeing coherent buffers is used in drivers/net/can/usb/kvaser_usb/kvaser_usb_core.c
Fixes: 51f3baad7de9 ("can: mcba_usb: Add support for Microchip CAN BUS Analyzer") Link: https://lore.kernel.org/r/20210609215833.30393-1-paskripkin@gmail.com Cc: linux-stable stable@vger.kernel.org Reported-and-tested-by: syzbot+57281c762a3922e14dfe@syzkaller.appspotmail.com Signed-off-by: Pavel Skripkin paskripkin@gmail.com Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- drivers/net/can/usb/mcba_usb.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c index 029e77dfa773..a45865bd7254 100644 --- a/drivers/net/can/usb/mcba_usb.c +++ b/drivers/net/can/usb/mcba_usb.c @@ -82,6 +82,8 @@ struct mcba_priv { bool can_ka_first_pass; bool can_speed_check; atomic_t free_ctx_cnt; + void *rxbuf[MCBA_MAX_RX_URBS]; + dma_addr_t rxbuf_dma[MCBA_MAX_RX_URBS]; };
/* CAN frame */ @@ -633,6 +635,7 @@ static int mcba_usb_start(struct mcba_priv *priv) for (i = 0; i < MCBA_MAX_RX_URBS; i++) { struct urb *urb = NULL; u8 *buf; + dma_addr_t buf_dma;
/* create a URB, and a buffer for it */ urb = usb_alloc_urb(0, GFP_KERNEL); @@ -642,7 +645,7 @@ static int mcba_usb_start(struct mcba_priv *priv) }
buf = usb_alloc_coherent(priv->udev, MCBA_USB_RX_BUFF_SIZE, - GFP_KERNEL, &urb->transfer_dma); + GFP_KERNEL, &buf_dma); if (!buf) { netdev_err(netdev, "No memory left for USB buffer\n"); usb_free_urb(urb); @@ -661,11 +664,14 @@ static int mcba_usb_start(struct mcba_priv *priv) if (err) { usb_unanchor_urb(urb); usb_free_coherent(priv->udev, MCBA_USB_RX_BUFF_SIZE, - buf, urb->transfer_dma); + buf, buf_dma); usb_free_urb(urb); break; }
+ priv->rxbuf[i] = buf; + priv->rxbuf_dma[i] = buf_dma; + /* Drop reference, USB core will take care of freeing it */ usb_free_urb(urb); } @@ -708,7 +714,14 @@ static int mcba_usb_open(struct net_device *netdev)
static void mcba_urb_unlink(struct mcba_priv *priv) { + int i; + usb_kill_anchored_urbs(&priv->rx_submitted); + + for (i = 0; i < MCBA_MAX_RX_URBS; ++i) + usb_free_coherent(priv->udev, MCBA_USB_RX_BUFF_SIZE, + priv->rxbuf[i], priv->rxbuf_dma[i]); + usb_kill_anchored_urbs(&priv->tx_submitted); }