[Qemu-devel] [PATCH] usb-ehci: Ensure frindex writes leave a valid frindex value

[Hans de Goede]

frindex is a 14 bits counter, so bits 31-14 should always be 0, and
after the commit titled "usb-ehci: frindex always is a 14 bits counter"
we rely on frindex always being a multiple of 8. I've not seen this in
practice, but theoretically a guest can write a value >= 0x4000 or a value
which is not a multiple of 8 value to frindex, this patch ensures that
things will still work when that happens.

Signed-off-by: Hans de Goede <address@hidden>
---
 hw/usb/hcd-ehci.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 64b58e3..8865b4e 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -1102,6 +1102,10 @@ static void ehci_mem_writel(void *ptr, 
target_phys_addr_t addr, uint32_t val)
         val &= USBINTR_MASK;
         break;
 
+    case FRINDEX:
+        val &= 0x00003ff8; /* frindex is 14bits and always a multiple of 8 */
+        break;
+
     case CONFIGFLAG:
         val &= 0x1;
         if (val) {
-- 
1.7.9.3