Emil Goode <emilgoode@xxxxxxxxx> writes: > This patch removes a generic hard_header_len check from the usbnet > module that is causing dropped packages under certain circumstances > for devices that send rx packets that cross urb boundaries. > > One example is the AX88772B which occasionally send rx packets that > cross urb boundaries where the remaining partial packet is sent with > no hardware header. When the buffer with a partial packet is of less > number of octets than the value of hard_header_len the buffer is > discarded by the usbnet module. > > With AX88772B this can be reproduced by using ping with a packet > size between 1965-1976. > > The bug has been reported here: > > https://bugzilla.kernel.org/show_bug.cgi?id=29082 > > This patch introduces the following changes: > - Removes the generic hard_header_len check in the rx_complete > function in the usbnet module. > - Introduces a ETH_HLEN check for skbs that are not cloned from > within a rx_fixup callback. > - For safety a hard_header_len check is added to each rx_fixup > callback function that could be affected by this change. > These extra checks could possibly be removed by someone > who has the hardware to test. > > The changes place full responsibility on the rx_fixup callback > functions that clone skbs to only pass valid skbs to the > usbnet_skb_return function. > > Signed-off-by: Emil Goode <emilgoode@xxxxxxxxx> > Reported-by: Igor Gnatenko <i.gnatenko.brain@xxxxxxxxx> Great work! Looks good to me. Just a couple of questions: > diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c > index ff5c871..b2e2aee 100644 > --- a/drivers/net/usb/qmi_wwan.c > +++ b/drivers/net/usb/qmi_wwan.c > @@ -80,10 +80,10 @@ static int qmi_wwan_rx_fixup(struct usbnet *dev, struct sk_buff *skb) > { > __be16 proto; > > - /* usbnet rx_complete guarantees that skb->len is at least > - * hard_header_len, so we can inspect the dest address without > - * checking skb->len > - */ > + /* This check is no longer done by usbnet */ > + if (skb->len < dev->net->hard_header_len) > + return 0; > + > switch (skb->data[0] & 0xf0) { > case 0x40: > proto = htons(ETH_P_IP); > diff --git a/drivers/net/usb/rndis_host.c b/drivers/net/usb/rndis_host.c > index a48bc0f..524a47a 100644 > --- a/drivers/net/usb/rndis_host.c > +++ b/drivers/net/usb/rndis_host.c > @@ -492,6 +492,10 @@ EXPORT_SYMBOL_GPL(rndis_unbind); > */ > int rndis_rx_fixup(struct usbnet *dev, struct sk_buff *skb) > { > + /* This check is no longer done by usbnet */ > + if (skb->len < dev->net->hard_header_len) > + return 0; > + Wouldn't it be better to test against ETH_HLEN, since that is a constant and "obviously correct" in this case? > diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c > index 4671da7..dd10d58 100644 > --- a/drivers/net/usb/usbnet.c > +++ b/drivers/net/usb/usbnet.c > @@ -542,17 +542,19 @@ static inline void rx_process (struct usbnet *dev, struct sk_buff *skb) > } > // else network stack removes extra byte if we forced a short packet > > - if (skb->len) { > - /* all data was already cloned from skb inside the driver */ > - if (dev->driver_info->flags & FLAG_MULTI_PACKET) > - dev_kfree_skb_any(skb); > - else > - usbnet_skb_return(dev, skb); > + /* all data was already cloned from skb inside the driver */ > + if (dev->driver_info->flags & FLAG_MULTI_PACKET) > + goto done; > + > + if (skb->len < ETH_HLEN) { > + dev->net->stats.rx_errors++; > + dev->net->stats.rx_length_errors++; > + netif_dbg(dev, rx_err, dev->net, "rx length %d\n", skb->len); > + } else { > + usbnet_skb_return(dev, skb); > return; > } > > - netif_dbg(dev, rx_err, dev->net, "drop\n"); > - dev->net->stats.rx_errors++; > done: > skb_queue_tail(&dev->done, skb); > } At first glance I wondered where the dev_kfree_skb_any(skb) went. But then I realized that you leave that to the common rx_cleanup path, using the dev->done queue. Is that right? If so, then I guess it could use a bit of explaining in the commit message? If I'm wrong, then I'm still looking for the explanation of where the dev_kfree_skb_any went :-) Bjørn -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
