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fib: use atomic_inc_not_zero() in fib_rules_lookup

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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>
This commit is contained in:
Eric Dumazet 2010-09-27 04:18:27 +00:00 committed by David S. Miller
parent 15fc1f7056
commit 7fa7cb7109
1 changed files with 5 additions and 3 deletions
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8
net/core/fib_rules.c
View file

@ -225,9 +225,11 @@ int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
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;
}
}