linux-kernel - [PATCH net] ipv4: ensure rcu_read_lock() in cipso_v4

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Date:   Fri, 21 Feb 2020 12:28:38 +0100
From:   Matteo Croce <mcroce@...hat.com>
To:     netdev@...r.kernel.org, linux-security-module@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Paul Moore <paul@...l-moore.com>,
        "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Guillaume Nault <gnault@...hat.com>,
        Eric Dumazet <eric.dumazet@...il.com>
Subject: [PATCH net] ipv4: ensure rcu_read_lock() in cipso_v4_error()

Similarly to commit c543cb4a5f07 ("ipv4: ensure rcu_read_lock() in
ipv4_link_failure()"), __ip_options_compile() must be called under rcu
protection.

Fixes: 3da1ed7ac398 ("net: avoid use IPCB in cipso_v4_error")
Suggested-by: Guillaume Nault <gnault@...hat.com>
Signed-off-by: Matteo Croce <mcroce@...hat.com>
---
 net/ipv4/cipso_ipv4.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
index 376882215919..0bd10a1f477f 100644
--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1724,6 +1724,7 @@ void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
 {
 	unsigned char optbuf[sizeof(struct ip_options) + 40];
 	struct ip_options *opt = (struct ip_options *)optbuf;
+	int res;
 
 	if (ip_hdr(skb)->protocol == IPPROTO_ICMP || error != -EACCES)
 		return;
@@ -1735,7 +1736,11 @@ void cipso_v4_error(struct sk_buff *skb, int error, u32 gateway)
 
 	memset(opt, 0, sizeof(struct ip_options));
 	opt->optlen = ip_hdr(skb)->ihl*4 - sizeof(struct iphdr);
-	if (__ip_options_compile(dev_net(skb->dev), opt, skb, NULL))
+	rcu_read_lock();
+	res = __ip_options_compile(dev_net(skb->dev), opt, skb, NULL);
+	rcu_read_unlock();
+
+	if (res)
 		return;
 
 	if (gateway)
-- 
2.24.1