tulip driver broken in v5.0.0-rc4

[Helge Deller]

In a qemu-system-hppa system, qemu release v5.0.0-rc, the tulip nic driver is broken.
The tulip nic is detected, even getting DHCP info does work.
But when trying to download bigger files via network, the tulip driver gets stuck.

For example when trying to download a 100MB file:

root@debian:~# wget https://speed.hetzner.de/100MB.bin
--2020-04-23 20:26:43-- https://speed.hetzner.de/100MB.bin
Resolving speed.hetzner.de (speed.hetzner.de)... 88.198.248.254, 2a01:4f8:0:59ed::2
Connecting to speed.hetzner.de (speed.hetzner.de)|88.198.248.254|:443... connected.
<waiting and stuck here>

When reverting this commit, everything works again:
commit 8ffb7265af64ec81748335ec8f20e7ab542c3850
Author: Prasad J Pandit <email address hidden>
Date: Tue Mar 24 22:57:22 2020 +0530
PATCH: net: tulip: check frame size and r/w data length

[Philippe Mathieu-Daudé (philmd)]

Commit 8ffb7265af does make the code safer, but broke the device model.
Instead of setting the error bits when the frame length is incorrect (too big), it simply discards it. The guest is not notified of the error and keeps waiting.

[Helge Deller (hdeller)]

Attached trivial patch fixes it.

[Thomas Huth (th-huth)]

Patch has been included here:
https://git.qemu.org/?p=qemu.git;a=commitdiff;h=d9b69640391618045