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AJvYcCUr3ZtqsZ+XvFvPsf7EB15/V9D+Js5SNHDkgCK1QzfBiJ2/wtOA9RY3XRDJZDlRFgE24oE+Rgg1@vger.kernel.org, AJvYcCVKklOTX26mA4BGg62YIpT4Kfc2pqg2aDZkTq/3Go5YeyptdSR5gZZ9gH4kKfaCKHmHwuWfzfGJoJ3UN60XXJk=@vger.kernel.org X-Gm-Message-State: AOJu0Yx+EQaXqKeY9rVnHOPnQnRbL3taVMYGPizkCYLyCV2MLcqi4HnH bVcTDGPlfBQTe9mtS1SvGCQOXixx3rTdBYHrVHhp4q7u48WTg66y0Y/1dw== X-Google-Smtp-Source: AGHT+IGq9JvfEkZmwPMa2lZzGZKak8jTwKZkT3pCyrwQTV+HHuGBoCtanFcoeGc8mG4qdJKn8Yefwg== X-Received: by 2002:a05:6512:2341:b0:536:554a:24c2 with SMTP id 2adb3069b0e04-53b348c8978mr18599811e87.13.1730804391074; Tue, 05 Nov 2024 02:59:51 -0800 (PST) Received: from [10.0.0.4] ([37.170.92.119]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4327d5e7c8bsm188562115e9.26.2024.11.05.02.59.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 05 Nov 2024 02:59:50 -0800 (PST) Message-ID: <7a2e5da2-5122-4c73-9a94-20e7f21a26f5@gmail.com> Date: Tue, 5 Nov 2024 11:59:49 +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 RFC 3/5] rtnetlink: do_setlink: Use sockaddr_storage To: Kees Cook , Jakub Kicinski Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-hardening@vger.kernel.org References: <20241104221450.work.053-kees@kernel.org> <20241104222513.3469025-3-kees@kernel.org> Content-Language: en-US From: Eric Dumazet In-Reply-To: <20241104222513.3469025-3-kees@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 11/4/24 11:25 PM, Kees Cook wrote: > Instead of a heap allocation use a stack allocated sockaddr_storage to > support arbitrary length addr_len value (but bounds check it against the > maximum address length). > > Signed-off-by: Kees Cook > --- > net/core/rtnetlink.c | 12 ++++-------- > 1 file changed, 4 insertions(+), 8 deletions(-) > > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c > index f0a520987085..eddd10b74f06 100644 > --- a/net/core/rtnetlink.c > +++ b/net/core/rtnetlink.c > @@ -2839,21 +2839,17 @@ static int do_setlink(const struct sk_buff *skb, > } > > if (tb[IFLA_ADDRESS]) { > - struct sockaddr *sa; > - int len; > + struct sockaddr_storage addr; > + struct sockaddr *sa = (struct sockaddr *)&addr; We already use too much stack space. Please move addr into struct rtnl_newlink_tbs ? > > - len = sizeof(sa_family_t) + max_t(size_t, dev->addr_len, > - sizeof(*sa)); > - sa = kmalloc(len, GFP_KERNEL); > - if (!sa) { > + if (dev->addr_len > sizeof(addr.__data)) { > err = -ENOMEM; > goto errout; > } > sa->sa_family = dev->type; > - memcpy(sa->sa_data, nla_data(tb[IFLA_ADDRESS]), > + memcpy(addr.__data, nla_data(tb[IFLA_ADDRESS]), > dev->addr_len); > err = dev_set_mac_address_user(dev, sa, extack); > - kfree(sa); > if (err) > goto errout; > status |= DO_SETLINK_MODIFIED;