Commit 8f716035 authored by Willem de Bruijn's avatar Willem de Bruijn Committed by Ben Hutchings

packet: fix tp_reserve race in packet_set_ring

commit c27927e3 upstream.

Updates to tp_reserve can race with reads of the field in
packet_set_ring. Avoid this by holding the socket lock during
updates in setsockopt PACKET_RESERVE.

This bug was discovered by syzkaller.

Fixes: 8913336a ("packet: add PACKET_RESERVE sockopt")
Reported-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarWillem de Bruijn <willemb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
parent 3557f62e
......@@ -3132,14 +3132,19 @@ 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;
if (val > INT_MAX)
return -EINVAL;
po->tp_reserve = val;
return 0;
lock_sock(sk);
if (po->rx_ring.pg_vec || po->tx_ring.pg_vec) {
ret = -EBUSY;
} else {
po->tp_reserve = val;
ret = 0;
}
release_sock(sk);
return ret;
}
case PACKET_LOSS:
{
......
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