From: David Miller <da...@davemloft.net> Date: Mon, Jun 1, 2020 at 11:32 AM -0700 > > From: Xie He <hexie3...@gmail.com> > Date: Wed, 27 May 2020 20:21:33 -0700 > > > When we use "AF_PACKET" sockets to send data directly over LAPB over > > Ethernet using this driver, the kernel will panic because of > > insufficient header space allocated in the "sk_buff" struct. > > > > The header space needs 18 bytes because: > > the lapbether driver will remove a pseudo header of 1 byte; > > the lapb module will prepend the LAPB header of 2 or 3 bytes; > > the lapbether driver will prepend a length field of 2 bytes and the > > Ethernet header of 14 bytes. > > > > So -1 + 3 + 16 = 18. > > > > Signed-off-by: Xie He <hexie3...@gmail.com> > > This is not the real problem. > > The real problem is that this is a stacked, layered, device and the > lapbether driver does not take the inner device's header length into > consideration. It should take this from the child device's netdev > structure rather than use constants. > > Your test case will still fail when lapbether is stacked on top of a > VLAN device or similar, even with your changes.
Thank you for your email! I'm sorry I didn't see your email previously because of problems with my mailbox. Yes, you are right. I'll use better ways to improve this and re-submit my patch. Thanks for pointing this out.
