Re: [PATCH net v1] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe

From: patchwork-bot+netdevbpf

Date: Wed Nov 12 2025 - 09:50:36 EST


Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@xxxxxxxxxx>:

On Tue, 11 Nov 2025 14:43:24 +0800 you wrote:
> The sit driver's packet transmission path calls: sit_tunnel_xmit() ->
> update_or_create_fnhe(), which lead to fnhe_remove_oldest() being called
> to delete entries exceeding FNHE_RECLAIM_DEPTH+random.
>
> The race window is between fnhe_remove_oldest() selecting fnheX for
> deletion and the subsequent kfree_rcu(). During this time, the
> concurrent path's __mkroute_output() -> find_exception() can fetch the
> soon-to-be-deleted fnheX, and rt_bind_exception() then binds it with a
> new dst using a dst_hold(). When the original fnheX is freed via RCU,
> the dst reference remains permanently leaked.
>
> [...]

Here is the summary with links:
- [net,v1] ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
https://git.kernel.org/netdev/net/c/ac1499fcd40f

You are awesome, thank you!
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