From: Paul Zimmerman <[email protected]>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    If you see a problem with using this for longterm, please comment.
                   -------------------

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 <[email protected]>
Signed-off-by: Sarah Sharp <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
---
 drivers/usb/host/xhci-ring.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index e4afa99..34ce5d4 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1716,7 +1716,7 @@ 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;
                }
-- 
1.7.4.4

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