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Message-Id: <20110305005637.606737417@clark.kroah.org>
Date: Fri, 04 Mar 2011 16:55:36 -0800
From: Greg KH <gregkh@...e.de>
To: linux-kernel@...r.kernel.org, stable@...nel.org
Cc: stable-review@...nel.org, torvalds@...ux-foundation.org,
akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
Paul Zimmerman <paulz@...opsys.com>,
Sarah Sharp <sarah.a.sharp@...ux.intel.com>
Subject: [31/73] xhci: Fix errors in the running total calculations in the TRB math
2.6.37-stable review patch. If anyone has any objections, please let us know.
------------------
From: Paul Zimmerman <Paul.Zimmerman@...opsys.com>
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 <paulz@...opsys.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
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++;
--
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