From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755878Ab1B1Qiq (ORCPT ); Mon, 28 Feb 2011 11:38:46 -0500 Received: from kroah.org ([198.145.64.141]:48305 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755841Ab1B1Qi0 (ORCPT ); Mon, 28 Feb 2011 11:38:26 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Feb 28 08:24:12 2011 Message-Id: <20110228162412.397726637@clark.kroah.org> User-Agent: quilt/0.48-11.2 Date: Mon, 28 Feb 2011 08:23:28 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Paul Zimmerman , Sarah Sharp Subject: [67/68] xhci: Fix errors in the running total calculations in the TRB math In-Reply-To: <20110228163502.GA27221@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let us know. ------------------ From: Paul Zimmerman commit 5807795bd4dececdf553719cc02869e633395787 upstream. Calculations like running_total = TRB_MAX_BUFF_SIZE - (sg_dma_address(sg) & (TRB_MAX_BUFF_SIZE - 1)); if (running_total != 0) num_trbs++; are incorrect, because running_total can never be zero, so the if() expression will never be true. I think the intention was that running_total be in the range of 0 to TRB_MAX_BUFF_SIZE-1, not 1 to TRB_MAX_BUFF_SIZE. So adding a running_total &= TRB_MAX_BUFF_SIZE - 1; fixes the problem. This patch should be queued for stable kernels back to 2.6.31. Signed-off-by: Paul Zimmerman Signed-off-by: Sarah Sharp Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/xhci-ring.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -1491,6 +1491,7 @@ static unsigned int count_sg_trbs_needed /* Scatter gather list entries may cross 64KB boundaries */ running_total = TRB_MAX_BUFF_SIZE - (sg_dma_address(sg) & (TRB_MAX_BUFF_SIZE - 1)); + running_total &= TRB_MAX_BUFF_SIZE - 1; if (running_total != 0) num_trbs++; @@ -1740,6 +1741,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd * /* How much data is (potentially) left before the 64KB boundary? */ running_total = TRB_MAX_BUFF_SIZE - (urb->transfer_dma & (TRB_MAX_BUFF_SIZE - 1)); + running_total &= TRB_MAX_BUFF_SIZE - 1; /* If there's some data on this 64KB chunk, or we have to send a * zero-length transfer, we need at least one TRB