From d434e5ac5d70e9da7d20e50246af9251a125bdad Mon Sep 17 00:00:00 2001 From: linzhecheng Date: Wed, 28 Mar 2018 21:34:35 +0800 Subject: [PATCH] virtio-serial: fix heap-over-flow Check device having the feature of VIRTIO_CONSOLE_F_EMERG_WRITE before get config->emerg_wr. It is neccessary because sizeof(virtio_console_config) is 8 byte if VirtIOSerial doesn't have the feature of VIRTIO_CONSOLE_F_EMERG_WRITE(see virtio_serial_device_realize), read/write emerg_wr will lead to heap-over-flow. Signed-off-by: linzhecheng Reviewed-by: Stefan Hajnoczi Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/char/virtio-serial-bus.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c index 9470bd7be7..d2dd8ab502 100644 --- a/hw/char/virtio-serial-bus.c +++ b/hw/char/virtio-serial-bus.c @@ -580,13 +580,16 @@ static void set_config(VirtIODevice *vdev, const uint8_t *config_data) VirtIOSerial *vser = VIRTIO_SERIAL(vdev); struct virtio_console_config *config = (struct virtio_console_config *)config_data; - uint8_t emerg_wr_lo = le32_to_cpu(config->emerg_wr); VirtIOSerialPort *port = find_first_connected_console(vser); VirtIOSerialPortClass *vsc; + uint8_t emerg_wr_lo; - if (!config->emerg_wr) { + if (!virtio_has_feature(vser->host_features, + VIRTIO_CONSOLE_F_EMERG_WRITE) || !config->emerg_wr) { return; } + + emerg_wr_lo = le32_to_cpu(config->emerg_wr); /* Make sure we don't misdetect an emergency write when the guest * does a short config write after an emergency write. */ config->emerg_wr = 0; -- GitLab