From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Qihang <q.h.hack.winter@gmail.com>, netdev@vger.kernel.org
Cc: willemdebruijn.kernel@gmail.com, daniel.zahka@gmail.com,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, horms@kernel.org, stable@vger.kernel.org,
Qihang <q.h.hack.winter@gmail.com>
Subject: Re: [PATCH net v5 2/2] packet: use consistent hard_header_len in TX_RING send path
Date: Thu, 30 Jul 2026 05:22:21 -0400 [thread overview]
Message-ID: <willemdebruijn.kernel.f39af6152c60@gmail.com> (raw)
In-Reply-To: <20260730082925.93759-3-q.h.hack.winter@gmail.com>
Qihang wrote:
> tpacket_snd() reads dev->hard_header_len independently for skb
> allocation and header construction in tpacket_fill_skb(). Concurrent
> netdevice reconfiguration can therefore make the reserved headroom
> smaller than the amount later pushed, or make copylen - hard_header_len
> negative.
>
> Snapshot hard_header_len once before processing ring frames and use it
> for the frame limit, headroom allocation, copy length, and skb
> construction. Pass the snapshot to tpacket_fill_skb().
>
> The separate SOCK_DGRAM consistency problem between hard_header_len and
> header_ops->create is not addressed here.
>
> Fixes: 69e3c75f4d54 ("net: TX_RING and packet mmap")
> Cc: stable@vger.kernel.org
> Signed-off-by: Qihang <q.h.hack.winter@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
prev parent reply other threads:[~2026-07-30 9:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-30 8:29 [PATCH net v5 0/2] packet: use consistent hard_header_len in send paths Qihang
2026-07-30 8:29 ` [PATCH net v5 1/2] packet: use consistent hard_header_len in non-ring " Qihang
2026-07-30 8:29 ` [PATCH net v5 2/2] packet: use consistent hard_header_len in TX_RING send path Qihang
2026-07-30 9:22 ` Willem de Bruijn [this message]
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