Re: [PATCH net] tun: Add missing bpf_net_ctx_clear() in do_xdp_generic()

[Jason Wang]

On Fri, Jul 26, 2024 at 5:41 AM Jeongjun Park <aha310510@xxxxxxxxx> wrote:
>
> There are cases where do_xdp_generic returns bpf_net_context without
> clearing it. This causes various memory corruptions, so the missing
> bpf_net_ctx_clear must be added.
>
> Reported-by: syzbot+44623300f057a28baf1e@xxxxxxxxxxxxxxxxxxxxxxxxx
> Fixes: fecef4cd42c6 ("tun: Assign missing bpf_net_context.")
> Signed-off-by: Jeongjun Park <aha310510@xxxxxxxxx>

Acked-by: Jason Wang <jasowang@xxxxxxxxxx>

(Looks like the do_xdp_generic() needs some tweak for example we can
merge the two paths for XDP_DROP at least).

Thanks

> ---
>  net/core/dev.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 6ea1d20676fb..751d9b70e6ad 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -5150,6 +5150,7 @@ int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff **pskb)
>                         bpf_net_ctx_clear(bpf_net_ctx);
>                         return XDP_DROP;
>                 }
> +               bpf_net_ctx_clear(bpf_net_ctx);
>         }
>         return XDP_PASS;
>  out_redir:
> --
>