From mboxrd@z Thu Jan 1 00:00:00 1970 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 0570728CF5A; Tue, 20 May 2025 22:31:17 +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=1747780280; cv=none; b=qSzIClY96bU+kEZgaw53NkJiXKyKRvBQcOMka1z8YXLBGqb2TZc2xjmrOYT5u5sxRKS7g/wRB2HrC7u7POjE2cV8gvgIjkwLDTxoMpdFJg6JBEgC7vwwr2fjXpHEZJ7me52V90riX0Lj1bTBbAGI4yp5u3GNSFCjkUao3CIJuj0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747780280; c=relaxed/simple; bh=7Qa/IpuQKFOWRWF79NofDyxxIjQyXX1yFfRlJmNAhpQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Od1IuAquD7TaIKFgB2xefclHTzL5xCeMISvQketTgW2BojjLXRi+LIB9g2HZGBnA+FHNyP1mpoMotzeX8HsCPl+w18URaJ2o/S1lfIgNPOGOA9ghSTO8UDkPZ24Y+Vn01z1SVjgc18XTH+i/vv5Qwuw4PICNQMXEh8KTZra/Muc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=A3CNK45I; 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="A3CNK45I" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 68716C4CEE9; Tue, 20 May 2025 22:31:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747780277; bh=7Qa/IpuQKFOWRWF79NofDyxxIjQyXX1yFfRlJmNAhpQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A3CNK45IECrwxZXZB1aQFv98sYIGatd3NboBjETrhzFHES169lc9By8gPOD0O1zez kCTJwjpPTMS/EQfaoANi5MzoudT2hf29ed6jzFdPrFcLGF184yDYdBrx/ArYN96B3N aDyXYFPu/pvGq5HgU8Of5vfhN08SjJ1OPjVGJSrotC3pefU28+HH2nJGdjtqCgQLSP d7Oqgz/qbIM5pfwhp24FZTMMjVdeWUHh4fg5/WcXlH4WGP+O62kTZb7mOFtgYmItX9 NMQhX4ruFsoui3VP521HFgtATQqun7PUag7YZ49uT5xR0Ehd5tVkDNFIXBSvJ1Gnmx sERkOUZi/KaOA== 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: target-devel@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 Content-Transfer-Encoding: 8bit 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; -- 2.34.1