From patchwork Tue May 20 22:31:06 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 891481 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 6CCF626462C; Tue, 20 May 2025 22:31:15 +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=1747780275; cv=none; b=rrPGJnaMH75ovdAYyr6Th35iEsKMcUfc5reKPyDLVEZgt5H9VHljPBMxmgNxfcLv8zvUOYIcyxZXfHdGl6MYeac4zI2Dfwk+ndMG5knyu5g3/2TK8Af39wwvqB0DjCUo/vhWa8l+DY6XCiNH86hMrpn+BdFwF8fiovENRKVCSU4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747780275; c=relaxed/simple; bh=7Qa/IpuQKFOWRWF79NofDyxxIjQyXX1yFfRlJmNAhpQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=FMGvzHCkuxWqFl+EdeIaiVXvWM22bM1XJy5kvTmjTryNWpe/9siMWQcQEU50HrVch5PMu2DM+GQA+KKftY3EDepBiQj5wCiiItWSzMh+Y8ue1eE+W9Hwp2K/UcdljULWD1lI4QK0DMDxxJSvDq4XpdM2Y4rcvM1R+v9WBnlsinA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BOwFhMEv; 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="BOwFhMEv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8CF8AC4CEF2; Tue, 20 May 2025 22:31:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747780274; bh=7Qa/IpuQKFOWRWF79NofDyxxIjQyXX1yFfRlJmNAhpQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BOwFhMEvnncEbt04sunuSxfflgKvjcUp7JSXl1Rx49NjhAjlJs3CnmgFEO2OjYLFS FnxMRf+Y0l8NIw9qbw2FBVhJEmGUfzmI3o5rYjb5Xats4x1tM2hRAQqRSZlsxW/PVs 99R5M0bnHfVohXHQoaW/qQCm7BPLAGEzVl0pXcL5Vst2Vc6khbh8bQjuyOktICMffX U3L1qVyImNx2jT/9p34tb3ykRcqoI2oa5OpAV4Lpy5hLXCv+0K7HtW4O6s6vPI/P8i l2MNooYeY9cP5g1ou6cmJiHAiz4cPxZ+ZQeRqLYZPnvcGd3eMSvAungNxE2YUbqYgG 83Ywtr100ZzXw== From: Kees Cook To: Kuniyuki Iwashima Cc: Kees Cook , Eric Dumazet , Jakub Kicinski , "David S. Miller" , Paolo Abeni , Simon Horman , Ido Schimmel , netdev@vger.kernel.org, Christoph Hellwig , Sagi Grimberg , Chaitanya Kulkarni , "Martin K. Petersen" , 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 , Eric Biggers , Milan Broz , Philipp Hahn , 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 7/7] rtnetlink: do_setlink: Use struct sockaddr_storage Date: Tue, 20 May 2025 15:31:06 -0700 Message-Id: <20250520223108.2672023-7-kees@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250520222452.work.063-kees@kernel.org> References: <20250520222452.work.063-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=2093; i=kees@kernel.org; h=from:subject; bh=7Qa/IpuQKFOWRWF79NofDyxxIjQyXX1yFfRlJmNAhpQ=; b=owGbwMvMwCVmps19z/KJym7G02pJDBm6TKtmnOlUkkri/PtTpKuJWcgyguPHyic/Ci2ju8tye j+JT8rrKGVhEONikBVTZAmyc49z8XjbHu4+VxFmDisTyBAGLk4BmIiyHcP/5OXSpk/zfC1KOKbI rnhQbaXzKEa72P+m2Oa4bIZV4bfXMzKsmyNVf+e5ovVutyS7NQKZupb5O/XKFvdZxT2fsS5DZR0 TAA== 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. 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;