From: Paul Zimmerman <Paul.Zimmerman@synopsys.com>
Date: Sat, 12 Feb 2011 22:07:57 +0000 (-0800)
Subject: xhci: Fix an error in count_sg_trbs_needed()
X-Git-Tag: v2.6.35.12~117
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0fa2aea484fd2fd9a713c77445a1bc49eafd3ad7;p=thirdparty%2Fkernel%2Fstable.git

xhci: Fix an error in count_sg_trbs_needed()

commit bcd2fde05341cef0052e49566ec88b406a521cf3 upstream.

The expression

	while (running_total < sg_dma_len(sg))

does not take into account that the remaining data length can be less
than sg_dma_len(sg). In that case, running_total can end up being
greater than the total data length, so an extra TRB is counted.
Changing the expression to

	while (running_total < sg_dma_len(sg) && running_total < temp)

fixes that.

This patch should be queued for stable kernels back to 2.6.31.

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 1801c56c8082d..4723a400d8687 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1896,7 +1896,7 @@ static unsigned int count_sg_trbs_needed(struct xhci_hcd *xhci, struct urb *urb)
 			num_trbs++;
 
 		/* How many more 64KB chunks to transfer, how many more TRBs? */
-		while (running_total < sg_dma_len(sg)) {
+		while (running_total < sg_dma_len(sg) && running_total < temp) {
 			num_trbs++;
 			running_total += TRB_MAX_BUFF_SIZE;
 		}