[NET]: Fix sk->sk_filter field access
Function sk_filter() is called from tcp_v{4,6}_rcv() functions with arg
needlock = 0, while socket is not locked at that moment. In order to avoid
this and similar issues in the future, use rcu for sk->sk_filter field read
protection.
Signed-off-by: Dmitry Mishin <dim@openvz.org>
Signed-off-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: Kirill Korotaev <dev@openvz.org>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 300215b..f4ccb90 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -427,21 +427,24 @@
}
#endif
-static inline unsigned run_filter(struct sk_buff *skb, struct sock *sk, unsigned res)
+static inline int run_filter(struct sk_buff *skb, struct sock *sk,
+ unsigned *snaplen)
{
struct sk_filter *filter;
+ int err = 0;
- bh_lock_sock(sk);
- filter = sk->sk_filter;
- /*
- * Our caller already checked that filter != NULL but we need to
- * verify that under bh_lock_sock() to be safe
- */
- if (likely(filter != NULL))
- res = sk_run_filter(skb, filter->insns, filter->len);
- bh_unlock_sock(sk);
+ rcu_read_lock_bh();
+ filter = rcu_dereference(sk->sk_filter);
+ if (filter != NULL) {
+ err = sk_run_filter(skb, filter->insns, filter->len);
+ if (!err)
+ err = -EPERM;
+ else if (*snaplen > err)
+ *snaplen = err;
+ }
+ rcu_read_unlock_bh();
- return res;
+ return err;
}
/*
@@ -491,13 +494,8 @@
snaplen = skb->len;
- if (sk->sk_filter) {
- unsigned res = run_filter(skb, sk, snaplen);
- if (res == 0)
- goto drop_n_restore;
- if (snaplen > res)
- snaplen = res;
- }
+ if (run_filter(skb, sk, &snaplen) < 0)
+ goto drop_n_restore;
if (atomic_read(&sk->sk_rmem_alloc) + skb->truesize >=
(unsigned)sk->sk_rcvbuf)
@@ -593,13 +591,8 @@
snaplen = skb->len;
- if (sk->sk_filter) {
- unsigned res = run_filter(skb, sk, snaplen);
- if (res == 0)
- goto drop_n_restore;
- if (snaplen > res)
- snaplen = res;
- }
+ if (run_filter(skb, sk, &snaplen) < 0)
+ goto drop_n_restore;
if (sk->sk_type == SOCK_DGRAM) {
macoff = netoff = TPACKET_ALIGN(TPACKET_HDRLEN) + 16;