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Date: Sat, 31 Jan 2026 22:00:03 +0100
From: Florian Westphal <fw@strlen.de>
To: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
	Paolo Abeni <pabeni@redhat.com>,
	"David S. Miller" <davem@davemloft.net>,
	netfilter-devel@vger.kernel.org, pablo@netfilter.org
Subject: Re: [PATCH v2 net-next 0/7] netfilter: updates for net-next
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 <20260130081245.6cacdde2@kernel.org>
 <aX0B1xaFGL43xxUn@strlen.de>
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Eric Dumazet <edumazet@google.com> wrote:
> > > Hi Florian, some more KASAN today:
> > >
> > > https://netdev-ctrl.bots.linux.dev/logs/vmksft/nf-dbg/results/496421/vm-crash-thr0-0
> >
> > > [ 1144.170509][   T12] ==================================================================
> > > [ 1144.170759][   T12] BUG: KASAN: slab-use-after-free in idr_for_each+0x1c1/0x1f0
> > > [ 1144.170922][   T12] Read of size 8 at addr ff11000012a16a70 by task kworker/u16:0/12
> > > [ 1144.171079][   T12]
> > > [ 1144.171133][   T12] CPU: 1 UID: 0 PID: 12 Comm: kworker/u16:0 Not tainted 6.19.0-rc7-virtme #1 PREEMPT(full)
> > > [ 1144.171137][   T12] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> > > [ 1144.171139][   T12] Workqueue: netns cleanup_net
> > > [ 1144.171145][   T12] Call Trace:
> > > [ 1144.171147][   T12]  <TASK>
> > > [ 1144.171149][   T12]  dump_stack_lvl+0x6f/0xa0
> > > [ 1144.171154][   T12]  print_address_description.constprop.0+0x6e/0x300
> > > [ 1144.171159][   T12]  print_report+0xfc/0x1fb
> > > [ 1144.171161][   T12]  ? idr_for_each+0x1c1/0x1f0
> > > [ 1144.171163][   T12]  ? __virt_addr_valid+0x1da/0x430
> > > [ 1144.171167][   T12]  ? idr_for_each+0x1c1/0x1f0
> > > [ 1144.171168][   T12]  kasan_report+0xe8/0x120
> >
> > Sigh.  Doesn't ring a bell, I will have a look.
> 
> Could this be related to "netns: optimize netns cleaning by batching
> unhash_nsid calls" ?

Thanks Eric, that seems plausible.

Did not yet have much luck with reproducing this so far, I will
look at this in more detail lon monday.