[Qemu-devel] [PATCH] usb: host-linux: Ignore parsing errors of the device descriptors

[Jan Kiszka]

The Linux is more tolerant here as well: Just stop parsing the device
descriptors when an error is detected but do not reset what was found
so far. This allows to run buggy devices with partially invalid
descriptors.

Signed-off-by: Jan Kiszka <address@hidden>
---
 hw/usb/host-linux.c |   31 +++++++++++--------------------
 1 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/hw/usb/host-linux.c b/hw/usb/host-linux.c
index 3a258b4..b8127e1 100644
--- a/hw/usb/host-linux.c
+++ b/hw/usb/host-linux.c
@@ -135,7 +135,7 @@ static int parse_filter(const char *spec, struct 
USBAutoFilter *f);
 static void usb_host_auto_check(void *unused);
 static int usb_host_read_file(char *line, size_t line_size,
                             const char *device_file, const char *device_name);
-static int usb_linux_update_endp_table(USBHostDevice *s);
+static void usb_linux_update_endp_table(USBHostDevice *s);
 
 static int usb_host_usbfs_type(USBHostDevice *s, USBPacket *p)
 {
@@ -1122,8 +1122,7 @@ static int usb_host_handle_control(USBDevice *dev, 
USBPacket *p,
     return USB_RET_ASYNC;
 }
 
-/* returns 1 on problem encountered or 0 for success */
-static int usb_linux_update_endp_table(USBHostDevice *s)
+static void usb_linux_update_endp_table(USBHostDevice *s)
 {
     static const char *tname[] = {
         [USB_ENDPOINT_XFER_CONTROL] = "control",
@@ -1149,23 +1148,23 @@ static int usb_linux_update_endp_table(USBHostDevice *s)
         if (d->bLength < 2) {
             trace_usb_host_parse_error(s->bus_num, s->addr,
                                        "descriptor too short");
-            goto error;
+            return;
         }
         if (i + d->bLength > s->descr_len) {
             trace_usb_host_parse_error(s->bus_num, s->addr,
                                        "descriptor too long");
-            goto error;
+            return;
         }
         switch (d->bDescriptorType) {
         case 0:
             trace_usb_host_parse_error(s->bus_num, s->addr,
                                        "invalid descriptor type");
-            goto error;
+            return;
         case USB_DT_DEVICE:
             if (d->bLength < 0x12) {
                 trace_usb_host_parse_error(s->bus_num, s->addr,
                                            "device descriptor too short");
-                goto error;
+                return;
             }
             v = (d->u.device.idVendor_hi << 8) | d->u.device.idVendor_lo;
             p = (d->u.device.idProduct_hi << 8) | d->u.device.idProduct_lo;
@@ -1175,7 +1174,7 @@ static int usb_linux_update_endp_table(USBHostDevice *s)
             if (d->bLength < 0x09) {
                 trace_usb_host_parse_error(s->bus_num, s->addr,
                                            "config descriptor too short");
-                goto error;
+                return;
             }
             configuration = d->u.config.bConfigurationValue;
             active = (configuration == s->dev.configuration);
@@ -1186,7 +1185,7 @@ static int usb_linux_update_endp_table(USBHostDevice *s)
             if (d->bLength < 0x09) {
                 trace_usb_host_parse_error(s->bus_num, s->addr,
                                            "interface descriptor too short");
-                goto error;
+                return;
             }
             interface = d->u.interface.bInterfaceNumber;
             altsetting = d->u.interface.bAlternateSetting;
@@ -1199,7 +1198,7 @@ static int usb_linux_update_endp_table(USBHostDevice *s)
             if (d->bLength < 0x07) {
                 trace_usb_host_parse_error(s->bus_num, s->addr,
                                            "endpoint descriptor too short");
-                goto error;
+                return;
             }
             devep = d->u.endpoint.bEndpointAddress;
             pid = (devep & USB_DIR_IN) ? USB_TOKEN_IN : USB_TOKEN_OUT;
@@ -1207,7 +1206,7 @@ static int usb_linux_update_endp_table(USBHostDevice *s)
             if (ep == 0) {
                 trace_usb_host_parse_error(s->bus_num, s->addr,
                                            "invalid endpoint address");
-                goto error;
+                return;
             }
 
             type = d->u.endpoint.bmAttributes & 0x3;
@@ -1240,11 +1239,6 @@ static int usb_linux_update_endp_table(USBHostDevice *s)
             break;
         }
     }
-    return 0;
-
-error:
-    usb_ep_reset(&s->dev);
-    return 1;
 }
 
 /*
@@ -1331,10 +1325,7 @@ static int usb_host_open(USBHostDevice *dev, int bus_num,
     }
 
     usb_ep_init(&dev->dev);
-    ret = usb_linux_update_endp_table(dev);
-    if (ret) {
-        goto fail;
-    }
+    usb_linux_update_endp_table(dev);
 
     if (speed == -1) {
         struct usbdevfs_connectinfo ci;
-- 
1.7.3.4