netdev - Re: [PATCH v1] bpf: Add length check for SK_DIAG_BPF_STORAGE_REQ_MAP

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Date: Mon, 24 Jul 2023 15:15:07 -0700
From: Jakub Kicinski <kuba@...nel.org>
To: Lin Ma <linma@....edu.cn>
Cc: davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
 ast@...nel.org, martin.lau@...nel.org, yhs@...com, andrii@...nel.org,
 void@...ifault.com, houtao1@...wei.com, laoar.shao@...il.com,
 inwardvessel@...il.com, kuniyu@...zon.com, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: Re: [PATCH v1] bpf: Add length check for
 SK_DIAG_BPF_STORAGE_REQ_MAP_FD parsing

On Sun, 23 Jul 2023 15:54:52 +0800 Lin Ma wrote:
> diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c
> index d4172534dfa8..6f1afbb394a6 100644
> --- a/net/core/bpf_sk_storage.c
> +++ b/net/core/bpf_sk_storage.c
> @@ -511,6 +511,11 @@ bpf_sk_storage_diag_alloc(const struct nlattr *nla_stgs)
>  		if (nla_type(nla) != SK_DIAG_BPF_STORAGE_REQ_MAP_FD)
>  			continue;
>  
> +		if (nla_len(nla) < sizeof(map_fd)) {
> +			err = -EINVAL;
> +			goto err_free;
> +		}

You can move this check earlier, when the attributes are getting
counted. That way we can avoid the alloc/free on error.