Commit fa18f36a authored by Gerd Hoffmann's avatar Gerd Hoffmann
Browse files

input: limit kbd queue depth 



Apply a limit to the number of items we accept into the keyboard queue.

Impact: Without this limit vnc clients can exhaust host memory by
sending keyboard events faster than qemu feeds them to the guest.

Fixes: CVE-2017-8379
Cc: P J P <ppandit@redhat.com>
Cc: Huawei PSIRT <PSIRT@huawei.com>
Reported-by: default avatar <jiangxin1@huawei.com>
Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Message-id: 20170428084237.23960-1-kraxel@redhat.com
parent e619b147

ui/input.c

+11 −3
Original line number Diff line number Diff line
@@ -41,6 +41,8 @@ static QTAILQ_HEAD(QemuInputEventQueueHead, QemuInputEventQueue) kbd_queue = 
    QTAILQ_HEAD_INITIALIZER(kbd_queue);

static QEMUTimer *kbd_timer;

static uint32_t kbd_default_delay_ms = 10;

static uint32_t queue_count;

static uint32_t queue_limit = 1024;



QemuInputHandlerState *qemu_input_handler_register(DeviceState *dev,

                                                   QemuInputHandler *handler)
@@ -268,6 +270,7 @@ static void qemu_input_queue_process(void *opaque) 
            break;

        }

        QTAILQ_REMOVE(queue, item, node);

        queue_count--;

        g_free(item);

    }

}
@@ -282,6 +285,7 @@ static void qemu_input_queue_delay(struct QemuInputEventQueueHead *queue, 
    item->delay_ms = delay_ms;

    item->timer = timer;

    QTAILQ_INSERT_TAIL(queue, item, node);

    queue_count++;



    if (start_timer) {

        timer_mod(item->timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL)
@@ -298,6 +302,7 @@ static void qemu_input_queue_event(struct QemuInputEventQueueHead *queue, 
    item->src = src;

    item->evt = evt;

    QTAILQ_INSERT_TAIL(queue, item, node);

    queue_count++;

}



static void qemu_input_queue_sync(struct QemuInputEventQueueHead *queue)
@@ -306,6 +311,7 @@ static void qemu_input_queue_sync(struct QemuInputEventQueueHead *queue) 


    item->type = QEMU_INPUT_QUEUE_SYNC;

    QTAILQ_INSERT_TAIL(queue, item, node);

    queue_count++;

}



void qemu_input_event_send_impl(QemuConsole *src, InputEvent *evt)
@@ -381,7 +387,7 @@ void qemu_input_event_send_key(QemuConsole *src, KeyValue *key, bool down) 
        qemu_input_event_send(src, evt);

        qemu_input_event_sync();

        qapi_free_InputEvent(evt);

    } else {

    } else if (queue_count < queue_limit) {

        qemu_input_queue_event(&kbd_queue, src, evt);

        qemu_input_queue_sync(&kbd_queue);

    }
@@ -409,9 +415,11 @@ void qemu_input_event_send_key_delay(uint32_t delay_ms) 
        kbd_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL, qemu_input_queue_process,

                                 &kbd_queue);

    }

    if (queue_count < queue_limit) {

        qemu_input_queue_delay(&kbd_queue, kbd_timer,

                               delay_ms ? delay_ms : kbd_default_delay_ms);

    }

}



InputEvent *qemu_input_event_new_btn(InputButton btn, bool down)

{