From patchwork Tue Dec 17 02:04:45 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 13910889 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0734F2B9CD; Tue, 17 Dec 2024 02:04:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734401090; cv=none; b=q2buxsfGB8Ay0kihLwnsKsEdRgkFSfey+Z7If8+qxiCKdvlHh9XrvsWU6RD4X5DmezYYYPrufKUVC4I+nvB/zEEVAhmBTmOI2V5MiL2gKcRPdpHMOIYSKmlaTUp7bSeMC64eGMQmnGUKqrUgwJKlhMWrujILC45dsFS4x3idpfI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734401090; c=relaxed/simple; bh=BTSN9M6hbNaevPQDTr9VKyPD+Neg+lgWqgTutRYqPCY=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=OVZAyMR8yov/BkIMU8QWC7z0XDpwR2hsJGEuJFjHwO4sUph2wIAdolaib9Vh1dR6JEU/SENBd2/UqGTp0vPxih1BibwPnPE/AeYuWIc1Fdyu6pSk3hpMc3xWIsJqiaCD4HzMB0Z9TQidBDvO/ZIjlvA4cX8WJYGl7kfVdLbm1HQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=f/vWsSpb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="f/vWsSpb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B769C4CED0; Tue, 17 Dec 2024 02:04:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734401089; bh=BTSN9M6hbNaevPQDTr9VKyPD+Neg+lgWqgTutRYqPCY=; h=From:To:Cc:Subject:Date:From; b=f/vWsSpbBzTQOBGM0w5uCSl+ZQvSYFYlQapLhFQYntwS1jttm4nWiQIU07/y9vyDq 50f1GB3KNjj/s4o+PTaiD8ceiFuHv8XNoseFnIqr7Ag7HnUnmGiYpwppylxBBC04UR 28AXlQrvAv6ICf0XFnEuklvyS8QXFM8pSXQWehsCBTQh3TxAmkW0j7V2eTaF6xk9RJ ACgEgFyDZArIgM0AhM9YDR0wUIQ9/YZOZLbwMlIdl4D42vl0sHkuVhKYwWybbR03X0 YmvKSdB273ddUzFcAZ8C3u3Mx6Zd9H6bdt4V0EevIpYz+MPGgBeHJ+JABElaKEHIuk Udms+ldyEiq+w== From: Kees Cook To: Eric Dumazet Cc: Kees Cook , "David S. Miller" , Jakub Kicinski , Paolo Abeni , Ido Schimmel , Petr Machata , netdev@vger.kernel.org, Simon Horman , Kuniyuki Iwashima , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] rtnetlink: do_setlink: Use true struct sockaddr Date: Mon, 16 Dec 2024 18:04:45 -0800 Message-Id: <20241217020441.work.066-kees@kernel.org> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1911; i=kees@kernel.org; h=from:subject:message-id; bh=BTSN9M6hbNaevPQDTr9VKyPD+Neg+lgWqgTutRYqPCY=; b=owGbwMvMwCVmps19z/KJym7G02pJDOkJd2yPbTCbxDi7of9UrHHKSbmkV8z8M2z6/LN2OFyqn yT/5LpqRykLgxgXg6yYIkuQnXuci8fb9nD3uYowc1iZQIYwcHEKwETMFRgZzlw/yPR5VveRV9Ic UyWCAsLYBC+4LzKar6LSKfgkhkViIcP/vKMCH4vrjZ4wvjc/9b6ghe3L2uj5sv9aOx142nyT9nf zAAA= X-Developer-Key: i=kees@kernel.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Instead of a heap allocation use a stack allocated struct sockaddr, as dev_set_mac_address_user() is the consumer (which uses a classic struct sockaddr). Cap the copy to the minimum address size between the incoming address and the traditional sa_data field itself. Putting "sa" on the stack means it will get a reused stack slot since it is smaller than other existing single-scope stack variables (like the vfinfo array). Signed-off-by: Kees Cook --- Cc: Eric Dumazet Cc: "David S. Miller" Cc: Jakub Kicinski Cc: Paolo Abeni Cc: Ido Schimmel Cc: Petr Machata Cc: netdev@vger.kernel.org --- net/core/rtnetlink.c | 22 +++++++--------------- 1 file changed, 7 insertions(+), 15 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index ab5f201bf0ab..6da0edc0870d 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3048,21 +3048,13 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev, } if (tb[IFLA_ADDRESS]) { - struct sockaddr *sa; - int len; - - len = sizeof(sa_family_t) + max_t(size_t, dev->addr_len, - sizeof(*sa)); - sa = kmalloc(len, GFP_KERNEL); - if (!sa) { - err = -ENOMEM; - goto errout; - } - sa->sa_family = dev->type; - memcpy(sa->sa_data, nla_data(tb[IFLA_ADDRESS]), - dev->addr_len); - err = dev_set_mac_address_user(dev, sa, extack); - kfree(sa); + struct sockaddr sa = { }; + + /* dev_set_mac_address_user() uses a true struct sockaddr. */ + sa.sa_family = dev->type; + memcpy(sa.sa_data, nla_data(tb[IFLA_ADDRESS]), + min(dev->addr_len, sizeof(sa.sa_data_min))); + err = dev_set_mac_address_user(dev, &sa, extack); if (err) goto errout; status |= DO_SETLINK_MODIFIED;