From patchwork Wed May 21 20:46:15 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 891628 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 85FDF2BE0E4; Wed, 21 May 2025 20:46:26 +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=1747860386; cv=none; b=D/assLVGrq9YnUuaXPRIwEP7Dno8sDSD7FZLzdFofBnJagdV05rjgMiv2FySy1i7yksvvSZ5uM5Y2vLQJaNQt6YkO+0NGCdW7iahxMRq2+pzXGfeyHQKT8eWpVubgvVc79v+IJgzZ4tKZzpT4aTb0vjAe4wRC8yn0J2RrhQzMtE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747860386; c=relaxed/simple; bh=l0FQvf1M3ScltpOkIqN+MDVq9vIgvD938vpt9yDUCJ4=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=JH5+ROpe5ossj7T489Jp9xVaT0qO/bzxX64M36esNcpDPySct5+fw68lTcIpM2Q2rF0BGqwf5uAbd+YK+fQxvBimdQ3qiQRzj2/vw1wZIp2v6QFaNW4Pm3K+QToG0lMonrurPVlZV9feVNaZt53dxw9DUOyb8YLGAYlZopUdlkA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GKUaA8HJ; 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="GKUaA8HJ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 092CDC4CEE4; Wed, 21 May 2025 20:46:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747860386; bh=l0FQvf1M3ScltpOkIqN+MDVq9vIgvD938vpt9yDUCJ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GKUaA8HJuMHueMQ43f9BlsAoZQ8tB64VoBZ0/vQHrZ1O00BzIgD1butpvZFA4qmyJ cmtBak74rNAZBzi78g9XCcOOzO2JmpmavrDdbeB3Cwr/o5KOy7ZAojs3PX0tYYFb2M kHLr0NLNigCJ/AH8PE8xnq2XeP8KOV7CEv+OtoG2KS4SxBJZ3960mSuTw1qlzyIaKj grOLGspy0g7sU6LfZH/6OqPD2P8wd6gzkc4oCoktcadVjIAv6+ACWXOfO6DB7CuXRj FDWLjqLvgOX1LAv9PbKRs+AJSEJeSW8jxouWJ8u+W5CxnAjL5ktbc6Ff3+HSqSTvxa mdP1RGY2gr7Cw== From: Kees Cook To: Kuniyuki Iwashima Cc: Kees Cook , "Gustavo A . R . Silva" , Eric Dumazet , Jakub Kicinski , "David S. Miller" , Paolo Abeni , Simon Horman , Ido Schimmel , netdev@vger.kernel.org, Willem de Bruijn , "Martin K. Petersen" , Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , Mike Christie , Max Gurtovoy , Maurizio Lombardi , Dmitry Bogdanov , Mingzhe Zou , Christophe Leroy , "Dr. David Alan Gilbert" , Andrew Lunn , Stanislav Fomichev , Cosmin Ratiu , Lei Yang , Samuel Mendoza-Jonas , Paul Fertser , Alexander Aring , Stefan Schmidt , Miquel Raynal , Hayes Wang , Douglas Anderson , Grant Grundler , Jay Vosburgh , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Jiri Pirko , Jason Wang , Vladimir Oltean , Florian Fainelli , Kory Maincent , Maxim Georgiev , Aleksander Jan Bajkowski , Philipp Hahn , Eric Biggers , Ard Biesheuvel , Al Viro , Ahmed Zaki , Alexander Lobakin , Xiao Liang , linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-wpan@vger.kernel.org, linux-usb@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH net-next v2 7/8] rtnetlink: do_setlink: Use struct sockaddr_storage Date: Wed, 21 May 2025 13:46:15 -0700 Message-Id: <20250521204619.2301870-7-kees@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250521204310.it.500-kees@kernel.org> References: <20250521204310.it.500-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2148; i=kees@kernel.org; h=from:subject; bh=l0FQvf1M3ScltpOkIqN+MDVq9vIgvD938vpt9yDUCJ4=; b=owGbwMvMwCVmps19z/KJym7G02pJDBl61tMbYmZ7vqv3y5thHs3r9nVXSVtZ7MEJ73YFLVVlf crw4fn/jlIWBjEuBlkxRZYgO/c4F4+37eHucxVh5rAygQxh4OIUgImYKjAyfDV1aEz44sad4qiz 39HRp5zLnFf5iffcMym3Px+wdE/gY/ineFOBL/PIyU28LFO3x+ZnOm9YpcfdFuQ7kyW368Lt3AU cAA== X-Developer-Key: i=kees@kernel.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Instead of a heap allocating a variably sized struct sockaddr and lying about the type in the call to netif_set_mac_address(), use a stack allocated struct sockaddr_storage. This lets us drop the cast and avoid the allocation. Putting "ss" on the stack means it will get a reused stack slot since it is the same size (128B) as other existing single-scope stack variables, like the vfinfo array (128B), so no additional stack space is used by this function. Acked-by: Gustavo A. R. Silva Signed-off-by: Kees Cook --- Cc: Kuniyuki Iwashima Cc: Eric Dumazet Cc: Jakub Kicinski Cc: "David S. Miller" Cc: Paolo Abeni Cc: Simon Horman Cc: Ido Schimmel Cc: --- net/core/rtnetlink.c | 19 ++++--------------- 1 file changed, 4 insertions(+), 15 deletions(-) diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c index 9743f1c2ae3c..f9a35bdc58ad 100644 --- a/net/core/rtnetlink.c +++ b/net/core/rtnetlink.c @@ -3080,17 +3080,7 @@ 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; + struct sockaddr_storage ss = { }; netdev_unlock_ops(dev); @@ -3098,10 +3088,9 @@ static int do_setlink(const struct sk_buff *skb, struct net_device *dev, down_write(&dev_addr_sem); netdev_lock_ops(dev); - memcpy(sa->sa_data, nla_data(tb[IFLA_ADDRESS]), - dev->addr_len); - err = netif_set_mac_address(dev, (struct sockaddr_storage *)sa, extack); - kfree(sa); + ss.ss_family = dev->type; + memcpy(ss.__data, nla_data(tb[IFLA_ADDRESS]), dev->addr_len); + err = netif_set_mac_address(dev, &ss, extack); if (err) { up_write(&dev_addr_sem); goto errout;