[PATCH 4.4 93/93] ipv4: ensure rcu_read_lock() in cipso_v4_error()

From: Greg Kroah-Hartman
Date: Thu Mar 19 2020 - 09:09:51 EST


From: Matteo Croce <mcroce@xxxxxxxxxx>

commit 3e72dfdf8227b052393f71d820ec7599909dddc2 upstream.

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@xxxxxxxxxx>
Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx>
Acked-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
net/ipv4/cipso_ipv4.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/ipv4/cipso_ipv4.c
+++ b/net/ipv4/cipso_ipv4.c
@@ -1809,6 +1809,7 @@ void cipso_v4_error(struct sk_buff *skb,
{
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;
@@ -1820,7 +1821,11 @@ void cipso_v4_error(struct sk_buff *skb,

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)