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authorEric Dumazet <edumazet@google.com>2017-02-14 09:03:51 -0800
committerDavid S. Miller <davem@davemloft.net>2017-02-14 15:05:12 -0500
commitd199fab63c11998a602205f7ee7ff7c05c97164b (patch)
tree9977e38c6afb849d7f823820b73d160092415e60 /net/packet
parentf39f0d1e1e93145a0e91d9a7a639c42fd037ecc3 (diff)
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packet: fix races in fanout_add()
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>
Diffstat (limited to 'net/packet')
-rw-r--r--net/packet/af_packet.c55
1 files changed, 30 insertions, 25 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d56ee46b11fc..0f03f6a53b4d 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1619,6 +1619,7 @@ static void fanout_release_data(struct packet_fanout *f)
static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
{
+ struct packet_rollover *rollover = NULL;
struct packet_sock *po = pkt_sk(sk);
struct packet_fanout *f, *match;
u8 type = type_flags & 0xff;
@@ -1641,23 +1642,28 @@ 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;
if (type == PACKET_FANOUT_ROLLOVER ||
(type_flags & PACKET_FANOUT_FLAG_ROLLOVER)) {
- po->rollover = kzalloc(sizeof(*po->rollover), GFP_KERNEL);
- if (!po->rollover)
- return -ENOMEM;
- atomic_long_set(&po->rollover->num, 0);
- atomic_long_set(&po->rollover->num_huge, 0);
- atomic_long_set(&po->rollover->num_failed, 0);
+ err = -ENOMEM;
+ rollover = kzalloc(sizeof(*rollover), GFP_KERNEL);
+ if (!rollover)
+ goto out;
+ atomic_long_set(&rollover->num, 0);
+ atomic_long_set(&rollover->num_huge, 0);
+ atomic_long_set(&rollover->num_failed, 0);
+ po->rollover = rollover;
}
- mutex_lock(&fanout_mutex);
match = NULL;
list_for_each_entry(f, &fanout_list, list) {
if (f->id == id &&
@@ -1704,11 +1710,11 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags)
}
}
out:
- mutex_unlock(&fanout_mutex);
- if (err) {
- kfree(po->rollover);
+ if (err && rollover) {
+ kfree(rollover);
po->rollover = NULL;
}
+ mutex_unlock(&fanout_mutex);
return err;
}
@@ -1717,23 +1723,22 @@ 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);
+ fanout_release_data(f);
+ kfree(f);
+ }
- if (atomic_dec_and_test(&f->sk_ref)) {
- list_del(&f->list);
- dev_remove_pack(&f->prot_hook);
- fanout_release_data(f);
- kfree(f);
+ if (po->rollover)
+ kfree_rcu(po->rollover, rcu);
}
mutex_unlock(&fanout_mutex);
-
- if (po->rollover)
- kfree_rcu(po->rollover, rcu);
}
static bool packet_extra_vlan_len_allowed(const struct net_device *dev,