netdev - Re: [PATCH net] tun: Add missing bpf_net_ctx_clear() in do_xdp

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Message-ID: <CACGkMEv2DZhp71-QdckH+9ycerdNd7+F5vFyq3g=qquEsm9rHw@mail.gmail.com>
Date: Fri, 26 Jul 2024 10:21:16 +0800
From: Jason Wang <jasowang@...hat.com>
To: Jeongjun Park <aha310510@...il.com>
Cc: syzbot+44623300f057a28baf1e@...kaller.appspotmail.com, davem@...emloft.net, 
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, ast@...nel.org, 
	daniel@...earbox.net, hawk@...nel.org, john.fastabend@...il.com, 
	willemdebruijn.kernel@...il.com, bigeasy@...utronix.de, bpf@...r.kernel.org, 
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH net] tun: Add missing bpf_net_ctx_clear() in do_xdp_generic()

On Fri, Jul 26, 2024 at 5:41 AM Jeongjun Park <aha310510@...il.com> 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@...kaller.appspotmail.com
> Fixes: fecef4cd42c6 ("tun: Assign missing bpf_net_context.")
> Signed-off-by: Jeongjun Park <aha310510@...il.com>

Acked-by: Jason Wang <jasowang@...hat.com>

(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:
> --
>