From fd891c9318b112462e54ee1b3b16b074b8bec5b1 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 e68be70b15..81488c48e2 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;