Re: [Bugme-new] [Bug 28552] New: ipheth stopped working between 2.6.35.9 and 2.6.36.2

(switched to email.  Please respond via emailed reply-to-all, not via the
bugzilla web interface).

On Mon, 7 Feb 2011 19:24:29 GMT
bugzilla-daemon@bugzilla.kernel.org wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=28552

           Summary: ipheth stopped working between 2.6.35.9 and 2.6.36.2
           Product: Drivers
           Version: 2.5
    Kernel Version: 2.6.36.2
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Network
        AssignedTo: drivers_network@kernel-bugs.osdl.org
        ReportedBy: linux-kernel@jmbreuer.net
        Regression: Yes


Created an attachment (id=46762)
 --> (https://bugzilla.kernel.org/attachment.cgi?id=46762)
tcpdump of iPhone tethering attempt in 2.6.36.2

Overview:

    Internet connection via iPhone 3G ("USB tethering") no longer works in
2.6.36.2; it appears that the packets coming from the iPhone are
misinterpreted.

Steps to Reproduce:

    1) Connect iPhone to computer via USB cable

    2) Put iPhone in "tethering" mode

Actual Results:

    The DHCP client times out trying to obtain a lease.

Expected Results: 

    The computer gets IP information via DHCP, and is able to share the
iPhone's internet connection.

Build Date & Platform: 

    2.6.36.2 on x86_64
    iPhone 3G Firmware 3.1.3

Additional Builds and Platforms:

    2.6.35.9 on x86_64 (same hardware) works as expected.

Additional Information:

    Attached are 2 tcpdump logs:
      2.6.36.2-tcpdump.txt in the failure case
      2.6.35.9-tcpdump.txt, working connection setup

Comparing the DHCP reply at 19:53:36.581403 (works) to 19:05:05.744666 (fails)
it appears that 2.6.36.2 misinterprets the data coming from the iPhone, so that
the failing packet is not recognized as an IP packet / valid DHCP reply.

The change to ipheth.c itself between 2.6.36 and 2.6.35 seems trivial:
http://lxr.free-electrons.com/diff/drivers/net/usb/ipheth.c?v=2.6.35;diffval=2.6.36;diffvar=v

Therefore I'd at first tried copying 2.6.35's ipheth.c into my 2.6.36 tree and
rebuilding this driver; it appears to fail the same as vanilla 2.6.36 does
[sorry, no logs - I can repeat this if required].

This suggests that the failure happens somewhere in either the networking or
USB layer, not the ipheth.c driver itself.

I'm happy to perform any additional testing required.