[Qemu-devel] [PATCH 2/3] usb: controllers do not need to check for babble themselves

[Hans de Goede <hdegoede@redhat.com>]

If an (emulated) usb-device tries to write more data to a packet then
its iov len, this will trigger an assert in usb_packet_copy(), and if
a driver somehow circumvents that check and writes more data to the
iov then there is space, we have a much bigger problem then not correctly
reporting babble to the guest.

In practice babble will only happen with (real) redirected devices, and there
both the usb-host os and the qemu usb-device code already check for it.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 hw/usb/hcd-ehci.c | 4 ----
 hw/usb/hcd-uhci.c | 5 -----
 2 files changed, 9 deletions(-)

diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index a6b8527..4750175 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -1460,10 +1460,6 @@ static void ehci_execute_complete(EHCIQueue *q)
             assert(0);
             break;
         }
-    } else if ((p->usb_status > p->tbytes) && (p->pid == USB_TOKEN_IN)) {
-        p->usb_status = USB_RET_BABBLE;
-        q->qh.token |= (QTD_TOKEN_HALT | QTD_TOKEN_BABBLE);
-        ehci_raise_irq(q->ehci, USBSTS_ERRINT);
     } else {
         // TODO check 4.12 for splits
 
diff --git a/hw/usb/hcd-uhci.c b/hw/usb/hcd-uhci.c
index 8987734..4e43d20 100644
--- a/hw/usb/hcd-uhci.c
+++ b/hw/usb/hcd-uhci.c
@@ -729,11 +729,6 @@ static int uhci_complete_td(UHCIState *s, UHCI_TD *td, UHCIAsync *async, uint32_
         *int_mask |= 0x01;
 
     if (pid == USB_TOKEN_IN) {
-        if (len > max_len) {
-            ret = USB_RET_BABBLE;
-            goto out;
-        }
-
         if ((td->ctrl & TD_CTRL_SPD) && len < max_len) {
             *int_mask |= 0x02;
             /* short packet: do not update QH */
-- 
1.7.11.4