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([2a01:4b00:bd1f:f500:f867:fc8a:5174:5755]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4891f98728dsm97277615e9.23.2026.04.23.16.50.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Apr 2026 16:50:35 -0700 (PDT) Message-ID: <8cc73c03-afb6-4b7d-97ea-e05d9cc56c2d@gmail.com> Date: Fri, 24 Apr 2026 00:50:34 +0100 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH bpf v1 1/1] bpf: Fix sk_local_storage diag dumping uninitialized special fields To: Amery Hung , bpf@vger.kernel.org Cc: netdev@vger.kernel.org, alexei.starovoitov@gmail.com, andrii@kernel.org, daniel@iogearbox.net, eddyz87@gmail.com, memxor@gmail.com, martin.lau@kernel.org, kernel-team@meta.com References: <20260423222356.155387-1-ameryhung@gmail.com> Content-Language: en-US From: Mykyta Yatsenko In-Reply-To: <20260423222356.155387-1-ameryhung@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 4/23/26 11:23 PM, Amery Hung wrote: > Call check_and_init_map_value() after the copy_map_value() to zero out > special field regions. diag_get() copies sk_local_storage map values > into a netlink message using copy_map_value{_locked}(), which > intentionally skip special fields. However, the destination buffer from > nla_reserve_64bit() is not zeroed and the skipped regions contain > uninitialized skb data can be sent to userspace. > > Fixes: 1ed4d92458a9 ("bpf: INET_DIAG support in bpf_sk_storage") > Signed-off-by: Amery Hung > --- > net/core/bpf_sk_storage.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c > index 14eb7812bda4..b50d26a542ed 100644 > --- a/net/core/bpf_sk_storage.c > +++ b/net/core/bpf_sk_storage.c > @@ -558,6 +558,7 @@ static int diag_get(struct bpf_local_storage_data *sdata, struct sk_buff *skb) > sdata->data, true); > else > copy_map_value(&smap->map, nla_data(nla_value), sdata->data); > + check_and_init_map_value(&smap->map, nla_data(nla_value)); > I think check_and_init_map_value() should be moved before the copy_map_value(), because copy_map_value_locked() already uses spin lock special field, which if uninitialized can deadlock? > nla_nest_end(skb, nla_stg); > return 0;