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authorWillem de Bruijn <willemb@google.com>2017-09-14 17:14:41 -0400
committerDavid S. Miller <davem@davemloft.net>2017-09-20 13:57:19 -0700
commit008ba2a13f2d04c947adc536d19debb8fe66f110 (patch)
treee6d5a2faacf4925192f0197f6cf60c5640a1cfaa /net/packet
parent35e015e1f5773417952fe91ce8790baf9b4237a2 (diff)
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packet: hold bind lock when rebinding to fanout hook
Packet socket bind operations must hold the po->bind_lock. This keeps po->running consistent with whether the socket is actually on a ptype list to receive packets. fanout_add unbinds a socket and its packet_rcv/tpacket_rcv call, then binds the fanout object to receive through packet_rcv_fanout. Make it hold the po->bind_lock when testing po->running and rebinding. Else, it can race with other rebind operations, such as that in packet_set_ring from packet_rcv to tpacket_rcv. Concurrent updates can result in a socket being added to a fanout group twice, causing use-after-free KASAN bug reports, among others. Reported independently by both trinity and syzkaller. Verified that the syzkaller reproducer passes after this patch. Fixes: dc99f600698d ("packet: Add fanout support.") Reported-by: nixioaming <nixiaoming@huawei.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
-rw-r--r--net/packet/af_packet.c16
1 files changed, 11 insertions, 5 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index c26172995511..d288f52c53f7 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1684,10 +1684,6 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
mutex_lock(&fanout_mutex);
- err = -EINVAL;
- if (!po->running)
- goto out;
-
err = -EALREADY;
if (po->fanout)
goto out;
@@ -1749,7 +1745,10 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
list_add(&match->list, &fanout_list);
}
err = -EINVAL;
- if (match->type == type &&
+
+ spin_lock(&po->bind_lock);
+ if (po->running &&
+ match->type == type &&
match->prot_hook.type == po->prot_hook.type &&
match->prot_hook.dev == po->prot_hook.dev) {
err = -ENOSPC;
@@ -1761,6 +1760,13 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
err = 0;
}
}
+ spin_unlock(&po->bind_lock);
+
+ if (err && !refcount_read(&match->sk_ref)) {
+ list_del(&match->list);
+ kfree(match);
+ }
+
out:
if (err && rollover) {
kfree(rollover);