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authorPavel Emelyanov <xemul@openvz.org>2007-10-17 21:22:42 -0700
committerDavid S. Miller <davem@davemloft.net>2007-10-17 21:22:42 -0700
commit47e958eac280c263397582d5581e868c3227a1bd (patch)
tree67fc50a26b7861b3330eae7f1874df851c0ef740 /net
parentd3904b739928edd83d117f1eb5bfa69f18d6f046 (diff)
[NET]: Fix the race between sk_filter_(de|at)tach and sk_clone()
The proposed fix is to delay the reference counter decrement until the quiescent state pass. This will give sk_clone() a chance to get the reference on the cloned filter. Regular sk_filter_uncharge can happen from the sk_free() only and there's no need in delaying the put - the socket is dead anyway and is to be release itself. Signed-off-by: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/filter.c23
1 files changed, 21 insertions, 2 deletions
diff --git a/net/core/filter.c b/net/core/filter.c
index 54dddc92452..1f0068eae50 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -387,6 +387,25 @@ int sk_chk_filter(struct sock_filter *filter, int flen)
}
/**
+ * sk_filter_rcu_release: Release a socket filter by rcu_head
+ * @rcu: rcu_head that contains the sk_filter to free
+ */
+static void sk_filter_rcu_release(struct rcu_head *rcu)
+{
+ struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
+
+ sk_filter_release(fp);
+}
+
+static void sk_filter_delayed_uncharge(struct sock *sk, struct sk_filter *fp)
+{
+ unsigned int size = sk_filter_len(fp);
+
+ atomic_sub(size, &sk->sk_omem_alloc);
+ call_rcu_bh(&fp->rcu, sk_filter_rcu_release);
+}
+
+/**
* sk_attach_filter - attach a socket filter
* @fprog: the filter program
* @sk: the socket to use
@@ -428,7 +447,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
rcu_assign_pointer(sk->sk_filter, fp);
rcu_read_unlock_bh();
- sk_filter_uncharge(sk, old_fp);
+ sk_filter_delayed_uncharge(sk, old_fp);
return 0;
}
@@ -441,7 +460,7 @@ int sk_detach_filter(struct sock *sk)
filter = rcu_dereference(sk->sk_filter);
if (filter) {
rcu_assign_pointer(sk->sk_filter, NULL);
- sk_filter_uncharge(sk, filter);
+ sk_filter_delayed_uncharge(sk, filter);
ret = 0;
}
rcu_read_unlock_bh();