From: Martin KaFai Lau <martin.lau@linux.dev>
To: Weiming Shi <bestswngs@gmail.com>
Cc: "David S . Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
Martin KaFai Lau <martin.lau@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Amery Hung <ameryhung@gmail.com>,
Leon Hwang <leon.hwang@linux.dev>, Kees Cook <kees@kernel.org>,
Fushuai Wang <wangfushuai@baidu.com>,
Menglong Dong <menglong8.dong@gmail.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
Xiang Mei <xmei5@asu.edu>
Subject: Re: [PATCH bpf] bpf: Fix NULL pointer dereference in bpf_sk_storage_clone and diag paths
Date: Mon, 20 Apr 2026 11:36:32 -0700 [thread overview]
Message-ID: <2026420182243.zAiN.martin.lau@linux.dev> (raw)
In-Reply-To: <20260420161432.3919396-2-bestswngs@gmail.com>
On Mon, Apr 20, 2026 at 09:14:33AM -0700, Weiming Shi wrote:
> diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
> index f8338acebf077..3b487280f50fa 100644
> --- a/net/core/bpf_sk_storage.c
> +++ b/net/core/bpf_sk_storage.c
> @@ -172,7 +172,7 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk)
> struct bpf_map *map;
>
> smap = rcu_dereference(SDATA(selem)->smap);
> - if (!(smap->map.map_flags & BPF_F_CLONE))
> + if (!smap || !(smap->map.map_flags & BPF_F_CLONE))
> continue;
>
> /* Note that for lockless listeners adding new element
> @@ -547,6 +547,8 @@ static int diag_get(struct bpf_local_storage_data *sdata, struct sk_buff *skb)
> return -EMSGSIZE;
>
> smap = rcu_dereference(sdata->smap);
> + if (!smap)
> + goto errout;
You need to study it more thoroughly and the code around it
instead of rushing to fix a problem discovered by AI/bot (?).
This is now treated as an -EMSGSIZE error by diag_get().
> if (nla_put_u32(skb, SK_DIAG_BPF_STORAGE_MAP_ID, smap->map.id))
> goto errout;
>
> @@ -599,6 +601,8 @@ static int bpf_sk_storage_diag_put_all(struct sock *sk, struct sk_buff *skb,
> saved_len = skb->len;
> hlist_for_each_entry_rcu(selem, &sk_storage->list, snode) {
> smap = rcu_dereference(SDATA(selem)->smap);
> + if (!smap)
> + continue;
> diag_size += nla_value_size(smap->map.value_size);
>
> if (nla_stgs && diag_get(SDATA(selem), skb))
... and here it will eventually return an -EMSGSIZE to the user space
which is incorrect. Pass the smap to diag_get instead.
pw-bot: cr
prev parent reply other threads:[~2026-04-20 18:36 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-20 16:14 [PATCH bpf] bpf: Fix NULL pointer dereference in bpf_sk_storage_clone and diag paths Weiming Shi
2026-04-20 18:36 ` Martin KaFai Lau [this message]
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