Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 07/15] packet: fix tp_reserve race in packet_set_ring | Date | Fri, 11 Aug 2017 15:02:21 -0700 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Willem de Bruijn <willemb@google.com>
[ Upstream commit c27927e372f0785f3303e8fad94b85945e2c97b7 ]
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: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt") Reported-by: Andrey Konovalov <andreyknvl@google.com> Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/packet/af_packet.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
--- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3622,14 +3622,19 @@ packet_setsockopt(struct socket *sock, i 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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