UPSTREAM: 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.
[js] no rollover in 3.12
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: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit 2a272abc4e543f488b3a73292ee75a06f20d077a)
Bug: 37897645
Change-Id: I3b021869ee26b88d10f4d6408ce34d351543ce74
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 05cfee7..2ae5ae2 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1429,13 +1429,16 @@
return -EINVAL;
}
- if (!po->running)
- return -EINVAL;
-
- if (po->fanout)
- return -EALREADY;
-
mutex_lock(&fanout_mutex);
+
+ err = -EINVAL;
+ if (!po->running)
+ goto out;
+
+ err = -EALREADY;
+ if (po->fanout)
+ goto out;
+
match = NULL;
list_for_each_entry(f, &fanout_list, list) {
if (f->id == id &&
@@ -1491,17 +1494,16 @@
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);
}
