From: Daniel Lezcano <dlezcano@fr.ibm.com>
Date: Sat, 19 Jan 2008 07:52:35 +0000 (-0800)
Subject: [IPV6]: Fix ip6_frag ctl
X-Git-Tag: firefly_0821_release~23655^2~275
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=7d460db953d6d205e4c8ecc2017aea1ec22b6c9a;p=firefly-linux-kernel-4.4.55.git

[IPV6]: Fix ip6_frag ctl

Alexey Dobriyan reported an oops when unsharing the network
indefinitely inside a loop. This is because the ip6_frag is not per
namespace while the ctls are.

That happens at the fragment timer expiration:
inet_frag_secret_rebuild function is called and this one restarts the
timer using the value stored inside the sysctl field.

        "mod_timer(&f->secret_timer, now + f->ctl->secret_interval);"

When the network is unshared, ip6_frag.ctl is initialized with the new
sysctl instances, but ip6_frag has only one instance. A race in this
case will appear because f->ctl can be modified during the read access
in the timer callback.

Until the ip6_frag is not per namespace, I discard the assignation to
the ctl field of ip6_frags in ip6_frag_sysctl_init when the network
namespace is not the init net.

Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv6/reassembly.c b/net/ipv6/reassembly.c
index 5cd0bc693a5f..4dfcddc871ce 100644
--- a/net/ipv6/reassembly.c
+++ b/net/ipv6/reassembly.c
@@ -627,6 +627,9 @@ static struct inet6_protocol frag_protocol =
 
 void ipv6_frag_sysctl_init(struct net *net)
 {
+	if (net != &init_net)
+		return;
+
 	ip6_frags.ctl = &net->ipv6.sysctl.frags;
 }