usb_fill_bulk_urb() receives buffer length parameter 8 bytes larger
than what's allocated by alloc_skb(); This seems to be a problem with
older (pegasus usb-1.1) devices, which may silently return more data
than the maximal packet length.

Going through the chip's documentation i figured out the ethernet
packet is appended with 4 bytes of status data.  That's why we now
subtract 4 instead of 8 bytes from the reported packet length.

Reported-by: Lincoln Ramsay <a1291...@gmail.com>
Signed-off-by: Petko Manolov <pet...@mip-labs.com>
---
 drivers/net/usb/pegasus.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c
index f840802..780c217 100644
--- a/drivers/net/usb/pegasus.c
+++ b/drivers/net/usb/pegasus.c
@@ -497,7 +497,7 @@ static void read_bulk_callback(struct urb *urb)
                pkt_len = buf[count - 3] << 8;
                pkt_len += buf[count - 4];
                pkt_len &= 0xfff;
-               pkt_len -= 8;
+               pkt_len -= 4;
        }
 
        /*
@@ -528,7 +528,7 @@ static void read_bulk_callback(struct urb *urb)
 goon:
        usb_fill_bulk_urb(pegasus->rx_urb, pegasus->usb,
                          usb_rcvbulkpipe(pegasus->usb, 1),
-                         pegasus->rx_skb->data, PEGASUS_MTU + 8,
+                         pegasus->rx_skb->data, PEGASUS_MTU,
                          read_bulk_callback, pegasus);
        rx_status = usb_submit_urb(pegasus->rx_urb, GFP_ATOMIC);
        if (rx_status == -ENODEV)
@@ -569,7 +569,7 @@ static void rx_fixup(unsigned long data)
        }
        usb_fill_bulk_urb(pegasus->rx_urb, pegasus->usb,
                          usb_rcvbulkpipe(pegasus->usb, 1),
-                         pegasus->rx_skb->data, PEGASUS_MTU + 8,
+                         pegasus->rx_skb->data, PEGASUS_MTU,
                          read_bulk_callback, pegasus);
 try_again:
        status = usb_submit_urb(pegasus->rx_urb, GFP_ATOMIC);
@@ -823,7 +823,7 @@ static int pegasus_open(struct net_device *net)
 
        usb_fill_bulk_urb(pegasus->rx_urb, pegasus->usb,
                          usb_rcvbulkpipe(pegasus->usb, 1),
-                         pegasus->rx_skb->data, PEGASUS_MTU + 8,
+                         pegasus->rx_skb->data, PEGASUS_MTU,
                          read_bulk_callback, pegasus);
        if ((res = usb_submit_urb(pegasus->rx_urb, GFP_KERNEL))) {
                if (res == -ENODEV)
-- 
2.8.0.rc3

Reply via email to