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packet: fix race condition in packet_set_ring #31

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Dec 6, 2016
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packet: fix race condition in packet_set_ring #31

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18 changes: 12 additions & 6 deletions net/packet/af_packet.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3649,19 +3649,25 @@ packet_setsockopt(struct socket *sock, int level, int optname, char __user *optv

if (optlen != sizeof(val))
return -EINVAL;
if (po->rx_ring.pg_vec || po->tx_ring.pg_vec)
return -EBUSY;
if (copy_from_user(&val, optval, sizeof(val)))
return -EFAULT;
switch (val) {
case TPACKET_V1:
case TPACKET_V2:
case TPACKET_V3:
po->tp_version = val;
return 0;
break;
default:
return -EINVAL;
}
lock_sock(sk);
if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) {
ret = -EBUSY;
} else {
po->tp_version = val;
ret = 0;
}
release_sock(sk);
return ret;
}
case PACKET_RESERVE:
{
Expand Down Expand Up @@ -4164,6 +4170,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
/* Added to avoid minimal code churn */
struct tpacket_req *req = &req_u->req;

lock_sock(sk);
/* Opening a Tx-ring is NOT supported in TPACKET_V3 */
if (!closing && tx_ring && (po->tp_version > TPACKET_V2)) {
net_warn_ratelimited("Tx-ring is not supported.\n");
Expand Down Expand Up @@ -4245,7 +4252,6 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
goto out;
}

lock_sock(sk);

/* Detach socket from network */
spin_lock(&po->bind_lock);
Expand Down Expand Up @@ -4294,11 +4300,11 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u,
if (!tx_ring)
prb_shutdown_retire_blk_timer(po, rb_queue);
}
release_sock(sk);

if (pg_vec)
free_pg_vec(pg_vec, order, req->tp_block_nr);
out:
release_sock(sk);
return err;
}

Expand Down