[PATCH AUTOSEL 5.19 29/73] netlink: Bounds-check struct nlmsgerr creation
From: Sasha Levin <sashal@kernel.org>
Date: 2022-10-09 22:27:40
Also in:
lkml, netfilter-devel, stable
Subsystem:
netfilter, networking [general], the rest · Maintainers:
Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
From: Kees Cook <redacted> [ Upstream commit 710d21fdff9a98d621cd4e64167f3ef8af4e2fd1 ] 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@kernel.org> Cc: Pablo Neira Ayuso <pablo@netfilter.org> Cc: Jozsef Kadlecsik <redacted> Cc: Florian Westphal <fw@strlen.de> Cc: "David S. Miller" <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Cc: Paolo Abeni <pabeni@redhat.com> Cc: syzbot <redacted> Cc: netfilter-devel@vger.kernel.org Cc: coreteam@netfilter.org Cc: netdev@vger.kernel.org Signed-off-by: Kees Cook <redacted> Link: https://lore.kernel.org/r/20220901071336.1418572-1-keescook@chromium.org (local) Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> --- net/netfilter/ipset/ip_set_core.c | 8 +++++--- net/netlink/af_netlink.c | 8 +++++--- 2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index 16ae92054baa..6b31746f9be3 100644
--- 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 *ctnl, struct sk_buff *skb, 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,
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 0cd91f813a3b..d8d3ed2096a3 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c@@ -2440,11 +2440,13 @@ void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err, 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) {
--
2.35.1