Re: [PATCH net v2] net: remove WARN_ON_ONCE() from the dev_fill_forward_path() loop check

[Jakub Kicinski]

On Sat, 12 Sep 2026 07:40:09 +0000 Farhad Alemi wrote:
> ipip_fill_forward_path() and ip6_tnl_fill_forward_path() look up the
> route to the tunnel's remote endpoint and set ctx->dev to its device,
> which is the tunnel itself when that route resolves back to the tunnel.
> dev_fill_forward_path() then makes no progress and trips
> WARN_ON_ONCE(last_dev == ctx->dev) as soon as a flowtable tries to
> offload a flow through the tunnel. That routing loop is a configuration
> any CAP_NET_ADMIN user can set up, and ip_tunnel_xmit() and
> ip6_tnl_xmit() already treat it as a tx error, so remove the warning and
> just fail the walk, as commit 008e7a7c293b ("net: remove WARN_ON_ONCE
> when accessing forward path array") did for the path stack overflow.
> 
> Fixes: ab427db17885 ("netfilter: flowtable: Add IPIP rx sw acceleration")
> Fixes: d98103575dcd ("netfilter: flowtable: Add IP6IP6 rx sw acceleration")
> Closes: https://lore.kernel.org/all/CA+0ovCgaRvbd0Udj70b2xxG8Cx3CaCpNhnf1V4RWQuDveZYZhA@xxxxxxxxxxxxxx/
> Suggested-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
> Assisted-by: Claude:claude-opus-5 syzkaller
> Signed-off-by: Farhad Alemi <farhad.alemi@xxxxxxxxxxxx>

Applied as 150dba2c69e933 in net, thanks
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pw-bot: accept