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author | Eric Dumazet <edumazet@google.com> | 2017-02-14 09:03:51 -0800 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2017-02-14 15:05:12 -0500 |
commit | d199fab63c11998a602205f7ee7ff7c05c97164b (patch) | |
tree | 9977e38c6afb849d7f823820b73d160092415e60 | |
parent | f39f0d1e1e93145a0e91d9a7a639c42fd037ecc3 (diff) | |
download | op-kernel-dev-d199fab63c11998a602205f7ee7ff7c05c97164b.zip op-kernel-dev-d199fab63c11998a602205f7ee7ff7c05c97164b.tar.gz |
packet: fix races in fanout_add()
Multiple threads can call fanout_add() at the same time.
We need to grab fanout_mutex earlier to avoid races that could
lead to one thread freeing po->rollover that was set by another thread.
Do the same in fanout_release(), for peace of mind, and to help us
finding lockdep issues earlier.
Fixes: dc99f600698d ("packet: Add fanout support.")
Fixes: 0648ab70afe6 ("packet: rollover prepare: per-socket state")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r-- | net/packet/af_packet.c | 55 |
1 files changed, 30 insertions, 25 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index d56ee46..0f03f6a 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1619,6 +1619,7 @@ static void fanout_release_data(struct packet_fanout *f) static int fanout_add(struct sock *sk, u16 id, u16 type_flags) { + struct packet_rollover *rollover = NULL; struct packet_sock *po = pkt_sk(sk); struct packet_fanout *f, *match; u8 type = type_flags & 0xff; @@ -1641,23 +1642,28 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) return -EINVAL; } + mutex_lock(&fanout_mutex); + + err = -EINVAL; if (!po->running) - return -EINVAL; + goto out; + err = -EALREADY; if (po->fanout) - return -EALREADY; + goto out; if (type == PACKET_FANOUT_ROLLOVER || (type_flags & PACKET_FANOUT_FLAG_ROLLOVER)) { - po->rollover = kzalloc(sizeof(*po->rollover), GFP_KERNEL); - if (!po->rollover) - return -ENOMEM; - atomic_long_set(&po->rollover->num, 0); - atomic_long_set(&po->rollover->num_huge, 0); - atomic_long_set(&po->rollover->num_failed, 0); + err = -ENOMEM; + rollover = kzalloc(sizeof(*rollover), GFP_KERNEL); + if (!rollover) + goto out; + atomic_long_set(&rollover->num, 0); + atomic_long_set(&rollover->num_huge, 0); + atomic_long_set(&rollover->num_failed, 0); + po->rollover = rollover; } - mutex_lock(&fanout_mutex); match = NULL; list_for_each_entry(f, &fanout_list, list) { if (f->id == id && @@ -1704,11 +1710,11 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) } } out: - mutex_unlock(&fanout_mutex); - if (err) { - kfree(po->rollover); + if (err && rollover) { + kfree(rollover); po->rollover = NULL; } + mutex_unlock(&fanout_mutex); return err; } @@ -1717,23 +1723,22 @@ static void fanout_release(struct sock *sk) struct packet_sock *po = pkt_sk(sk); struct packet_fanout *f; - f = po->fanout; - if (!f) - return; - mutex_lock(&fanout_mutex); - po->fanout = NULL; + f = po->fanout; + if (f) { + po->fanout = NULL; + + if (atomic_dec_and_test(&f->sk_ref)) { + list_del(&f->list); + dev_remove_pack(&f->prot_hook); + fanout_release_data(f); + kfree(f); + } - if (atomic_dec_and_test(&f->sk_ref)) { - list_del(&f->list); - dev_remove_pack(&f->prot_hook); - fanout_release_data(f); - kfree(f); + if (po->rollover) + kfree_rcu(po->rollover, rcu); } mutex_unlock(&fanout_mutex); - - if (po->rollover) - kfree_rcu(po->rollover, rcu); } static bool packet_extra_vlan_len_allowed(const struct net_device *dev, |