diff options
| author | Eric Dumazet <edumazet@google.com> | 2017-02-14 09:03:51 -0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2017-03-16 02:18:50 +0000 |
| commit | 382299a020add34cc75ac501bbcb655195c123b8 (patch) | |
| tree | f288911744900d7251e5a9136a7dbb35d59d06ca /net | |
| parent | 1560f610f60a24bfd8808ac4ac7b6ab38a80811d (diff) | |
packet: fix races in fanout_add()
commit d199fab63c11998a602205f7ee7ff7c05c97164b upstream.
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>
[bwh: Backported to 3.2:
- No rollover queue stats
- Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'net')
| -rw-r--r-- | net/packet/af_packet.c | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index dae9476fa4d8..146b2d7567c0 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1286,13 +1286,16 @@ 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 && @@ -1348,17 +1351,16 @@ static void fanout_release(struct sock *sk) struct packet_sock *po = pkt_sk(sk); struct packet_fanout *f; + mutex_lock(&fanout_mutex); f = po->fanout; - if (!f) - return; + if (f) { + po->fanout = NULL; - po->fanout = NULL; - - mutex_lock(&fanout_mutex); - 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); } |