From 3dc42254ec97e2feca16a7d02eafffcc8e0a0a34 Mon Sep 17 00:00:00 2001 From: Andriy Gapon Date: Thu, 22 Dec 2011 11:34:30 +0200 Subject: [PATCH] usb-ohci: td.cbp incorrectly updated near page end The current code that updates the cbp value after a transfer looks like this: td.cbp += ret; if ((td.cbp & 0xfff) + ret > 0xfff) { because the 'ret' value is effectively added twice the check may fire too early when the overflow hasn't happened yet. Below is one of the possible changes that correct the behavior: Signed-off-by: Gerd Hoffmann --- hw/usb-ohci.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/hw/usb-ohci.c b/hw/usb-ohci.c index c2981c5..c27014a 100644 --- a/hw/usb-ohci.c +++ b/hw/usb-ohci.c @@ -1025,10 +1025,10 @@ static int ohci_service_td(OHCIState *ohci, struct ohci_ed *ed) if (ret == len) { td.cbp = 0; } else { - td.cbp += ret; if ((td.cbp & 0xfff) + ret > 0xfff) { - td.cbp &= 0xfff; - td.cbp |= td.be & ~0xfff; + td.cbp = (td.be & ~0xfff) + ((td.cbp + ret) & 0xfff); + } else { + td.cbp += ret; } } td.flags |= OHCI_TD_T1; -- 2.7.4