diff options
| author | Willem de Bruijn <willemb@google.com> | 2017-09-14 17:14:41 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-09-20 13:57:19 -0700 |
| commit | 008ba2a13f2d04c947adc536d19debb8fe66f110 (patch) | |
| tree | e6d5a2faacf4925192f0197f6cf60c5640a1cfaa | |
| parent | 35e015e1f5773417952fe91ce8790baf9b4237a2 (diff) | |
| download | linux-008ba2a13f2d04c947adc536d19debb8fe66f110.tar.gz | |
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>
| -rw-r--r-- | net/packet/af_packet.c | 16 |
1 files changed, 11 insertions, 5 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index c26172995511f7..d288f52c53f7c1 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); |