Subject: Re: [TEST] nft_tproxy_udp.sh flaky after Fedora 44 upgrade

From: Florian Westphal <[email-masked]>
Date: Thu, 9 Apr 2026 20:28:40 +0200

Florian Westphal <[email-masked]> wrote:
> Jakub Kicinski <[email-masked]> wrote:
> > When you have a sec -- we upgraded the NIPA systems to Fedora 44
> > over the weekend, and nft_tproxy_udp.sh has gotten quite flaky:
> > https://netdev.bots.linux.dev/contest.html?test=nft-tproxy-udp-sh
> > 
> > One thing that we hit immediately is this, in case tproxy test
> > uses socat:
> > 
> > commit e65d8b6f3092398efd7c74e722cb7a516d9a0d6d
> > Date:   Sat Apr 4 16:01:03 2026 -0700
> > 
> >     selftests: drv-net: adjust to socat changes
> >     
> >     socat v1.8.1.0 now defaults to shut-null, it sends an extra
> >     0-length UDP packet when sender disconnects. This breaks
> >     our tests which expect the exact packet sequence.
> >     
> >     Add shut-none which was the old default where necessary.
> 
> Thanks for the pointer, I will try to get to this later today.

No luck so far:

# grep PASS /tmp/log |wc -l
900
# grep -v PASS /tmp/log
# cat /etc/fedora-release
Fedora release 44 (Forty Four)

This on
commit d444044483a98264722ff77ffef407df0589c6c7 (HEAD, nipa/net-next-2026-04-09--06-00)
with a debug build.
(non debug did not trigger anything either).