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Date: Wed, 12 Aug 2026 18:22:46 -0700
From: Jakub Kicinski <kuba@kernel.org>
To: David Lee <david.lee@trailofbits.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>, davem@davemloft.net,
 edumazet@google.com, pabeni@redhat.com, jiri@resnulli.us, Kyle Zeng
 <kylebot@openai.com>, "Dominik 'Disconnect3d' Czarnota"
 <dominik.czarnota@trailofbits.com>, horms@kernel.org,
 netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] net/sched: defer qdisc freeing after failed
 creation
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On Tue, 11 Aug 2026 00:58:27 +0900 David Lee wrote:
> [  230.057740] ipip: IPv4 and MPLS over IPv4 tunneling driver
> [  231.667279]
> ==================================================================
> [  231.667738] BUG: KASAN: stack-out-of-bounds in
> __ip_options_echo+0xdf7/0x1860

I'm struggling to see how this is a repro for the qdisc lifecycle bug

In any case -- if the fix is really correct and there's some real repro
shared off list - I think you're deleting the last caller of
qdisc_free() so you should inline it into qdisc_free_cb()

So patch as is needs to be refactored. But please don't repost just
to refactor, we need a convincing repro first.