xhci driver may in some special cases need to copy small amounts of payload data to a bounce buffer in order to meet the boundary and alignment restrictions set by the xHCI specification.

In the majority of these cases the data is in a sg list, and driver incorrectly assumed data is always in urb->sg when using the bounce buffer.

If data instead is contiguous, and in urb->transfer_buffer, we may still need to bounce buffer a small part if data starts very close (less than packet size) to a 64k boundary.

Check if sg list is used before copying data to/from it.

Fixes: f9c589e142d0 ("xhci: TD-fragment, align the unsplittable case with a bounce buffer") Cc: stable@vger.kernel.org Reported-by: Andreas Hartmann andihartmann@01019freenet.de Tested-by: Andreas Hartmann andihartmann@01019freenet.de Signed-off-by: Mathias Nyman mathias.nyman@linux.intel.com --- drivers/usb/host/xhci-ring.c | 31 ++++++++++++++++++++----------- 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index cf0c93a90200..89c3be9917f6 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -699,11 +699,16 @@ static void xhci_unmap_td_bounce_buffer(struct xhci_hcd *xhci, dma_unmap_single(dev, seg->bounce_dma, ring->bounce_buf_len, DMA_FROM_DEVICE); /* for in tranfers we need to copy the data from bounce to sg */ - len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs, seg->bounce_buf, - seg->bounce_len, seg->bounce_offs); - if (len != seg->bounce_len) - xhci_warn(xhci, "WARN Wrong bounce buffer read length: %zu != %d\n", - len, seg->bounce_len); + if (urb->num_sgs) { + len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs, seg->bounce_buf, + seg->bounce_len, seg->bounce_offs); + if (len != seg->bounce_len) + xhci_warn(xhci, "WARN Wrong bounce buffer read length: %zu != %d\n", + len, seg->bounce_len); + } else { + memcpy(urb->transfer_buffer + seg->bounce_offs, seg->bounce_buf, + seg->bounce_len); + } seg->bounce_len = 0; seg->bounce_offs = 0; } @@ -3277,12 +3282,16 @@ static int xhci_align_td(struct xhci_hcd *xhci, struct urb *urb, u32 enqd_len,

/* create a max max_pkt sized bounce buffer pointed to by last trb */ if (usb_urb_dir_out(urb)) { - len = sg_pcopy_to_buffer(urb->sg, urb->num_sgs, - seg->bounce_buf, new_buff_len, enqd_len); - if (len != new_buff_len) - xhci_warn(xhci, - "WARN Wrong bounce buffer write length: %zu != %d\n", - len, new_buff_len); + if (urb->num_sgs) { + len = sg_pcopy_to_buffer(urb->sg, urb->num_sgs, + seg->bounce_buf, new_buff_len, enqd_len); + if (len != new_buff_len) + xhci_warn(xhci, "WARN Wrong bounce buffer write length: %zu != %d\n", + len, new_buff_len); + } else { + memcpy(seg->bounce_buf, urb->transfer_buffer + enqd_len, new_buff_len); + } + seg->bounce_dma = dma_map_single(dev, seg->bounce_buf, max_pkt, DMA_TO_DEVICE); } else {