From: Eric Dumazet edumazet@google.com
This patch has been added to the stable tree. If you have any objections, please let us know.
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[ Upstream commit d199fab63c11998a602205f7ee7ff7c05c97164b ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- net/packet/af_packet.c | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 4cd7e27e3fc4..88cec9576e93 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1447,13 +1447,16 @@ 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;
- mutex_lock(&fanout_mutex); match = NULL; list_for_each_entry(f, &fanout_list, list) { if (f->id == id && @@ -1509,17 +1512,16 @@ 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); - kfree(f); + if (atomic_dec_and_test(&f->sk_ref)) { + list_del(&f->list); + dev_remove_pack(&f->prot_hook); + kfree(f); + } } mutex_unlock(&fanout_mutex); }