From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760414Ab1CEBAW (ORCPT ); Fri, 4 Mar 2011 20:00:22 -0500 Received: from kroah.org ([198.145.64.141]:50251 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760380Ab1CEBAQ (ORCPT ); Fri, 4 Mar 2011 20:00:16 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Fri Mar 4 16:56:37 2011 Message-Id: <20110305005637.606737417@clark.kroah.org> User-Agent: quilt/0.48-11.2 Date: Fri, 04 Mar 2011 16:55:36 -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: [31/73] xhci: Fix errors in the running total calculations in the TRB math In-Reply-To: <20110305005720.GA16162@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.37-stable 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 | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -2375,6 +2375,7 @@ 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++; @@ -2661,6 +2662,7 @@ 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 @@ -2877,6 +2879,7 @@ static int count_isoc_trbs_needed(struct td_len = urb->iso_frame_desc[i].length; running_total = TRB_MAX_BUFF_SIZE - (addr & (TRB_MAX_BUFF_SIZE - 1)); + running_total &= TRB_MAX_BUFF_SIZE - 1; if (running_total != 0) num_trbs++;