linux-kernel - [PATCH nf] netfilter: ensure rcu_read_lock() in ipv4_find

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Message-Id: <20200224185529.50530-1-mcroce@redhat.com>
Date:   Mon, 24 Feb 2020 19:55:29 +0100
From:   Matteo Croce <mcroce@...hat.com>
To:     netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Stephen Suryaputra <ssuryaextr@...il.com>
Subject: [PATCH nf] netfilter: ensure rcu_read_lock() in ipv4_find_option()

As in commit c543cb4a5f07 ("ipv4: ensure rcu_read_lock() in ipv4_link_failure()")
and commit 3e72dfdf8227 ("ipv4: ensure rcu_read_lock() in cipso_v4_error()"),
__ip_options_compile() must be called under rcu protection.

Fixes: dbb5281a1f84 ("netfilter: nf_tables: add support for matching IPv4 options")
Signed-off-by: Matteo Croce <mcroce@...hat.com>
---
 net/netfilter/nft_exthdr.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c
index a5e8469859e3..752264b3043a 100644
--- a/net/netfilter/nft_exthdr.c
+++ b/net/netfilter/nft_exthdr.c
@@ -77,6 +77,7 @@ static int ipv4_find_option(struct net *net, struct sk_buff *skb,
 	bool found = false;
 	__be32 info;
 	int optlen;
+	int ret;
 
 	iph = skb_header_pointer(skb, 0, sizeof(_iph), &_iph);
 	if (!iph)
@@ -95,7 +96,11 @@ static int ipv4_find_option(struct net *net, struct sk_buff *skb,
 		return -EBADMSG;
 	opt->optlen = optlen;
 
-	if (__ip_options_compile(net, opt, NULL, &info))
+	rcu_read_lock();
+	ret = __ip_options_compile(net, opt, NULL, &info);
+	rcu_read_unlock();
+
+	if (ret)
 		return -EBADMSG;
 
 	switch (target) {
-- 
2.24.1