netdev - [PATCH net-next 4/4] ipv6: protect flow label renew against GC

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Message-Id: <1383661738-6083-4-git-send-email-florent.fourcot@enst-bretagne.fr>
Date:	Tue,  5 Nov 2013 15:28:58 +0100
From:	Florent Fourcot <florent.fourcot@...t-bretagne.fr>
To:	netdev@...r.kernel.org
Cc:	Florent Fourcot <florent.fourcot@...t-bretagne.fr>
Subject: [PATCH net-next 4/4] ipv6: protect flow label renew against GC

Take ip6_fl_lock before to read and update a
label. It prevents race condition if GC is
running.

Reported-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
Signed-off-by: Florent Fourcot <florent.fourcot@...t-bretagne.fr>
---
 net/ipv6/ip6_flowlabel.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
index 41ced9c..1d2fc48 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -540,11 +540,13 @@ int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
 		return -ESRCH;
 
 	case IPV6_FL_A_RENEW:
+		spin_lock_bh(&ip6_fl_lock);
 		rcu_read_lock_bh();
 		for_each_sk_fl_rcu(np, sfl) {
 			if (sfl->fl->label == freq.flr_label) {
 				err = fl6_renew(sfl->fl, freq.flr_linger, freq.flr_expires);
 				rcu_read_unlock_bh();
+				spin_unlock_bh(&ip6_fl_lock);
 				return err;
 			}
 		}
@@ -555,10 +557,12 @@ int ipv6_flowlabel_opt(struct sock *sk, char __user *optval, int optlen)
 			fl = fl_lookup(net, freq.flr_label);
 			if (fl) {
 				err = fl6_renew(fl, freq.flr_linger, freq.flr_expires);
+				spin_unlock_bh(&ip6_fl_lock);
 				fl_release(fl);
 				return err;
 			}
 		}
+		spin_unlock_bh(&ip6_fl_lock);
 		return -ESRCH;
 
 	case IPV6_FL_A_GET:
-- 
1.8.4.rc3

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