As noticed by Lincoln Ramsay <a1291...@gmail.com> some old (usb 1.1) Pegasus based devices may actually return more bytes than the specified in the datasheet amount. That would not be a problem if the allocated space for the SKB was equal to the parameter passed to usb_fill_bulk_urb(). Some poor bugger (i really hope it was not me, but 'git blame' is useless in this case, so anyway) decided to add '+ 8' to the buffer length parameter. Sometimes the usb transfer overflows and corrupts the socket structure, leading to kernel panic.
The above doesn't seem to happen for newer (Pegasus2 based) devices which did help this bug to hide for so long. Nearly all Pegasus devices may append the RX status to the end of the received packet. It is the default setup for the driver. The actual ethernet packet is 4 bytes shorter. Why and when 'pkt_len -= 4' became 'pkt_len -= 8' is again hidden in the mists of time. There might have been a good reason to do so, but multiple reads of the datasheet did not point me to any. The patch is against v4.6-rc5 and was tested on ADM8515 device by transferring multiple gigabytes of data over a couple of days without any complaints from the kernel. Changes since v1: - split the patch in two parts; - corrected the subject lines; Petko Manolov (2): pegasus: fixes URB buffer allocation size; pegasus: fixes reported packet length drivers/net/usb/pegasus.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) -- 2.8.0.rc3
