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virtio-serial: fix heapover-flow

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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 <linzhecheng@huawei.com>
Message-Id: <20180328133435.20112-1-linzhecheng@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
linzhecheng 2018-03-28 21:34:35 +08:00 committed by Paolo Bonzini
parent c2b01cfec1
commit 9f91022f28
1 changed files with 5 additions and 2 deletions
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7
hw/char/virtio-serial-bus.c
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@ -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;