netdev - [PATCH 6.0 306/314] netlink: Bounds-check struct nlmsgerr creation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20221123084639.430560487@linuxfoundation.org>
Date:   Wed, 23 Nov 2022 09:52:31 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        patches@...ts.linux.dev, Jakub Kicinski <kuba@...nel.org>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        syzbot <syzkaller@...glegroups.com>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, Kees Cook <keescook@...omium.org>
Subject: [PATCH 6.0 306/314] netlink: Bounds-check struct nlmsgerr creation

From: Kees Cook <keescook@...omium.org>

commit 710d21fdff9a98d621cd4e64167f3ef8af4e2fd1 upstream.

In preparation for FORTIFY_SOURCE doing bounds-check on memcpy(),
switch from __nlmsg_put to nlmsg_put(), and explain the bounds check
for dealing with the memcpy() across a composite flexible array struct.
Avoids this future run-time warning:

  memcpy: detected field-spanning write (size 32) of single field "&errmsg->msg" at net/netlink/af_netlink.c:2447 (size 16)

Cc: Jakub Kicinski <kuba@...nel.org>
Cc: Pablo Neira Ayuso <pablo@...filter.org>
Cc: Jozsef Kadlecsik <kadlec@...filter.org>
Cc: Florian Westphal <fw@...len.de>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Paolo Abeni <pabeni@...hat.com>
Cc: syzbot <syzkaller@...glegroups.com>
Cc: netfilter-devel@...r.kernel.org
Cc: coreteam@...filter.org
Cc: netdev@...r.kernel.org
Signed-off-by: Kees Cook <keescook@...omium.org>
Link: https://lore.kernel.org/r/20220901071336.1418572-1-keescook@chromium.org
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/netfilter/ipset/ip_set_core.c |    8 +++++---
 net/netlink/af_netlink.c          |    8 +++++---
 2 files changed, 10 insertions(+), 6 deletions(-)

--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -1719,11 +1719,13 @@ call_ad(struct net *net, struct sock *ct
 		skb2 = nlmsg_new(payload, GFP_KERNEL);
 		if (!skb2)
 			return -ENOMEM;
-		rep = __nlmsg_put(skb2, NETLINK_CB(skb).portid,
-				  nlh->nlmsg_seq, NLMSG_ERROR, payload, 0);
+		rep = nlmsg_put(skb2, NETLINK_CB(skb).portid,
+				nlh->nlmsg_seq, NLMSG_ERROR, payload, 0);
 		errmsg = nlmsg_data(rep);
 		errmsg->error = ret;
-		memcpy(&errmsg->msg, nlh, nlh->nlmsg_len);
+		unsafe_memcpy(&errmsg->msg, nlh, nlh->nlmsg_len,
+			      /* Bounds checked by the skb layer. */);
+
 		cmdattr = (void *)&errmsg->msg + min_len;
 
 		ret = nla_parse(cda, IPSET_ATTR_CMD_MAX, cmdattr,
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2440,11 +2440,13 @@ void netlink_ack(struct sk_buff *in_skb,
 		return;
 	}
 
-	rep = __nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
-			  NLMSG_ERROR, payload, flags);
+	rep = nlmsg_put(skb, NETLINK_CB(in_skb).portid, nlh->nlmsg_seq,
+			NLMSG_ERROR, payload, flags);
 	errmsg = nlmsg_data(rep);
 	errmsg->error = err;
-	memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg) ? nlh->nlmsg_len : sizeof(*nlh));
+	unsafe_memcpy(&errmsg->msg, nlh, payload > sizeof(*errmsg)
+					 ? nlh->nlmsg_len : sizeof(*nlh),
+		      /* Bounds checked by the skb layer. */);
 
 	if (nlk_has_extack && extack) {
 		if (extack->_msg) {