From: Victor Nogueira <victor@mojatatu.com>
To: Ren Wei <enjou1224z@gmail.com>,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org
Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, horms@kernel.org, jhs@mojatatu.com,
jiri@resnulli.us, vega@nebusec.ai, milkory@outlook.com
Subject: Re: [PATCH net v2 1/2] net/sched: reject overly deep qdisc hierarchies
Date: Sat, 1 Aug 2026 13:27:50 -0300 [thread overview]
Message-ID: <7a0d6b21-a10d-4310-9202-4262bb50c354@mojatatu.com> (raw)
In-Reply-To: <1e9ab39597423fd5d13cfaaf52279b8ee3d9fc3c.1785434373.git.milkory@outlook.com>
On 01/08/2026 10:42, Ren Wei wrote:
> From: Zijie Huang <milkory@outlook.com>
>
> Deep qdisc hierarchies can lead to excessive recursion in qdisc tree
> walkers and exhaust the kernel stack. The existing loop check does not
> cover the create-and-graft path, so a hierarchy can still be extended by
> creating a new child qdisc below an already deep parent.
>
> Store the hierarchy depth in struct Qdisc and update it when qdiscs are
> grafted. Reject new child qdiscs once the parent is already at the maximum
> allowed depth.
>
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable@vger.kernel.org
> Reported-by: Vega <vega@nebusec.ai>
> Assisted-by: Codex:gpt-5.4
> Signed-off-by: Zijie Huang <milkory@outlook.com>
> Signed-off-by: Ren Wei <enjou1224z@gmail.com>
Reviewed-by: Victor Nogueira <victor@mojatatu.com>
next prev parent reply other threads:[~2026-08-01 16:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-01 13:42 [PATCH net v2 0/2] net/sched: fix qdisc graft hierarchy validation Ren Wei
2026-08-01 13:42 ` [PATCH net v2 1/2] net/sched: reject overly deep qdisc hierarchies Ren Wei
2026-08-01 14:11 ` Jamal Hadi Salim
2026-08-01 14:30 ` Zijie Huang
2026-08-01 16:27 ` Victor Nogueira [this message]
2026-08-01 13:42 ` [PATCH net v2 2/2] selftests/tc-testing: add qdisc hierarchy depth tests Ren Wei
2026-08-01 16:35 ` Victor Nogueira
2026-08-01 14:13 ` [PATCH net v2 0/2] net/sched: fix qdisc graft hierarchy validation Jamal Hadi Salim
2026-08-06 13:40 ` patchwork-bot+netdevbpf
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