* [PATCH] Fixes buffer allocation size and the actual packet length; @ 2016-04-26 18:50 Petko Manolov 2016-04-26 18:50 ` Petko Manolov 2016-04-26 19:45 ` David Miller 0 siblings, 2 replies; 3+ messages in thread From: Petko Manolov @ 2016-04-26 18:50 UTC (permalink / raw) To: netdev; +Cc: davem, petkan As noticed by Lincoln Ramsay <a1291762@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 complains from the kernel. Petko Manolov (1): Fixes buffer allocation size and the actual packet length; drivers/net/usb/pegasus.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) -- 2.8.0.rc3 ^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH] Fixes buffer allocation size and the actual packet length; 2016-04-26 18:50 [PATCH] Fixes buffer allocation size and the actual packet length; Petko Manolov @ 2016-04-26 18:50 ` Petko Manolov 2016-04-26 19:45 ` David Miller 1 sibling, 0 replies; 3+ messages in thread From: Petko Manolov @ 2016-04-26 18:50 UTC (permalink / raw) To: netdev; +Cc: davem, petkan 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 <a1291762@gmail.com> Signed-off-by: Petko Manolov <petkan@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 ^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] Fixes buffer allocation size and the actual packet length; 2016-04-26 18:50 [PATCH] Fixes buffer allocation size and the actual packet length; Petko Manolov 2016-04-26 18:50 ` Petko Manolov @ 2016-04-26 19:45 ` David Miller 1 sibling, 0 replies; 3+ messages in thread From: David Miller @ 2016-04-26 19:45 UTC (permalink / raw) To: petkan; +Cc: netdev Submitting a cover letter and the patch itself with identical Subject lines is not correct. You must also use proper "[PATCH $(TREE) X/Y] " prefixes in your Subject lines as well. Please format your Subject lines correctly and resubmit, thank you. ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2016-04-26 19:45 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2016-04-26 18:50 [PATCH] Fixes buffer allocation size and the actual packet length; Petko Manolov 2016-04-26 18:50 ` Petko Manolov 2016-04-26 19:45 ` David Miller
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