From 8db36e9dddb1b6fab3554a8c00d92268b33a487b Mon Sep 17 00:00:00 2001 From: Alon Levy Date: Sun, 26 Feb 2012 17:09:21 +0100 Subject: [PATCH] usb-desc: fix user trigerrable segfaults (!config) Check for dev->config being NULL in two places: USB_REQ_GET_CONFIGURATION and USB_REQ_GET_STATUS. The behavior of USB_REQ_GET_STATUS is unspecified in the Default state, that corresponds to dev->config being NULL (it defaults to NULL and is reset whenever a SET_CONFIGURATION with value 0, or attachment). I implemented it to correspond with the state before ed5a83ddd8c1d8ec7b1015315530cf29949e7c48, the commit moving SET_STATUS to usb-desc; if dev->config is not set we return whatever is in the first configuration. The behavior of USB_REQ_GET_CONFIGURATION is also undefined before any SET_CONFIGURATION, but here we just return 0 (same as specified for the Address state). A win7 guest failed to initialize the device before this patch, segfaulting when GET_STATUS was called with dev->config == NULL. With this patch the passthrough device still doesn't work but the failure is unrelated. Signed-off-by: Alon Levy Signed-off-by: Gerd Hoffmann --- hw/usb-desc.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/hw/usb-desc.c b/hw/usb-desc.c index 3c3ed6a802..ccf85ade9e 100644 --- a/hw/usb-desc.c +++ b/hw/usb-desc.c @@ -536,7 +536,11 @@ int usb_desc_handle_control(USBDevice *dev, USBPacket *p, break; case DeviceRequest | USB_REQ_GET_CONFIGURATION: - data[0] = dev->config->bConfigurationValue; + /* + * 9.4.2: 0 should be returned if the device is unconfigured, otherwise + * the non zero value of bConfigurationValue. + */ + data[0] = dev->config ? dev->config->bConfigurationValue : 0; ret = 1; break; case DeviceOutRequest | USB_REQ_SET_CONFIGURATION: @@ -544,9 +548,18 @@ int usb_desc_handle_control(USBDevice *dev, USBPacket *p, trace_usb_set_config(dev->addr, value, ret); break; - case DeviceRequest | USB_REQ_GET_STATUS: + case DeviceRequest | USB_REQ_GET_STATUS: { + const USBDescConfig *config = dev->config ? + dev->config : &dev->device->confs[0]; + data[0] = 0; - if (dev->config->bmAttributes & 0x40) { + /* + * Default state: Device behavior when this request is received while + * the device is in the Default state is not specified. + * We return the same value that a configured device would return if + * it used the first configuration. + */ + if (config->bmAttributes & 0x40) { data[0] |= 1 << USB_DEVICE_SELF_POWERED; } if (dev->remote_wakeup) { @@ -555,6 +568,7 @@ int usb_desc_handle_control(USBDevice *dev, USBPacket *p, data[1] = 0x00; ret = 2; break; + } case DeviceOutRequest | USB_REQ_CLEAR_FEATURE: if (value == USB_DEVICE_REMOTE_WAKEUP) { dev->remote_wakeup = 0;