From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-fw-9106.amazon.com (smtp-fw-9106.amazon.com [207.171.188.206]) (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 1A3492595; Tue, 17 Dec 2024 02:42:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=207.171.188.206 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734403332; cv=none; b=AgpFaFCr2QApAvMkdzI+J7j3QBldeEwrHegcssm5iMGlrc4Qy5iQzoSjikQRpZ2FPRUudzkrIS8dvIIK8QdQ02kP3XRdi17g0hYR3BOIF/DPzgKwHDYR+jQawrsxNdO6MyRRbG2lBhnfMxVpgVrrGFO30R1KEZTci/gCKzqDaec= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734403332; c=relaxed/simple; bh=sxZHwktHLbmobkjo0Mrad2ue1QYN50MUOr5DU5+0mFc=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=h0Plriq9BWPvHaP7P+NsaU7SumM29OvspHeF/sod+EXcZaiuKl02wR5mvy+kf/InUMKaa6T5qO9xdtcc/DfCKSCtTw6pPf63HmK3bl6LMZRi3n234q08HmRxf4xu81QeaQKoAoELrTPGSba9JgfeNncokdS28D9PqBx/clUqEx0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.jp; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=YC8e+IbU; arc=none smtp.client-ip=207.171.188.206 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.jp Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="YC8e+IbU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1734403333; x=1765939333; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=7u6OT2PYujYQCUkhEoUVtOLDlI0hXd4C0CDZ9AuT7gs=; b=YC8e+IbUWloKA9Ax6yn77qlO9f4CwKpiUIEg7t4ALpy6vAmk10h/ovsY 2TP961Su11a0fAksjlUnmwROd4AiAzY/VeWa6C1whrjpgl4DFAz6XI6Bk p9BUMNcY7qiS+IpawKsWR8ML1BpPXgdVNCXj+vitA7KPxm+pgbFt+sQYZ Q=; X-IronPort-AV: E=Sophos;i="6.12,240,1728950400"; d="scan'208";a="783912395" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO smtpout.prod.us-west-2.prod.farcaster.email.amazon.dev) ([10.25.36.210]) by smtp-border-fw-9106.sea19.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2024 02:42:07 +0000 Received: from EX19MTAUWB002.ant.amazon.com [10.0.7.35:35891] by smtpin.naws.us-west-2.prod.farcaster.email.amazon.dev [10.0.59.52:2525] with esmtp (Farcaster) id b97cbbc6-b57a-4b3f-b068-55f90e4c1c6a; Tue, 17 Dec 2024 02:42:05 +0000 (UTC) X-Farcaster-Flow-ID: b97cbbc6-b57a-4b3f-b068-55f90e4c1c6a Received: from EX19D004ANA001.ant.amazon.com (10.37.240.138) by EX19MTAUWB002.ant.amazon.com (10.250.64.231) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.39; Tue, 17 Dec 2024 02:42:04 +0000 Received: from 6c7e67c6786f.amazon.com (10.118.246.225) by EX19D004ANA001.ant.amazon.com (10.37.240.138) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.1258.39; Tue, 17 Dec 2024 02:42:00 +0000 From: Kuniyuki Iwashima To: CC: , , , , , , , , , , Subject: Re: [PATCH] rtnetlink: do_setlink: Use true struct sockaddr Date: Tue, 17 Dec 2024 11:41:56 +0900 Message-ID: <20241217024156.43328-1-kuniyu@amazon.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) In-Reply-To: <20241217020441.work.066-kees@kernel.org> References: <20241217020441.work.066-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: EX19D040UWB002.ant.amazon.com (10.13.138.89) To EX19D004ANA001.ant.amazon.com (10.37.240.138) From: Kees Cook Date: Mon, 16 Dec 2024 18:04:45 -0800 > 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). I remember Eric's feedback was to keep using heap instead of stack because rtnl_newlink() path already uses too much on stack. > 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; > -- > 2.34.1