From 7fa7cb7109d07c29ab28bb877bc7049a0150dbe5 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Mon, 27 Sep 2010 04:18:27 +0000
Subject: [PATCH] fib: use atomic_inc_not_zero() in fib_rules_lookup
It seems we dont use appropriate refcount increment in an
rcu_read_lock() protected section.
fib_rule_get() might increment a null refcount and bad things could
happen.
While fib_nl_delrule() respects an rcu grace period before calling
fib_rule_put(), fib_rules_cleanup_ops() calls fib_rule_put() without a
grace period.
Note : after this patch, we might avoid the synchronize_rcu() call done
in fib_nl_delrule()
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/core/fib_rules.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/net/core/fib_rules.c b/net/core/fib_rules.c
index 42e84e08a1be..d0787284cb07 100644
--- a/net/core/fib_rules.c
+++ b/net/core/fib_rules.c
@@ -225,9 +225,11 @@ jumped:
err = ops->action(rule, fl, flags, arg);
if (err != -EAGAIN) {
- fib_rule_get(rule);
- arg->rule = rule;
- goto out;
+ if (likely(atomic_inc_not_zero(&rule->refcnt))) {
+ arg->rule = rule;
+ goto out;
+ }
+ break;
}
}
--
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