From 2fa88daa6f299bfb83672c3b525d786ad03b4735 Mon Sep 17 00:00:00 2001 From: Sarah Sharp Date: Tue, 3 Nov 2009 22:02:24 -0800 Subject: USB: xhci: Fix TRB physical to virtual address translation. The trb_in_td() function in the xHCI driver is supposed to translate a physical transfer buffer request (TRB) into a virtual pointer to the ring segment that TRB is in. Unfortunately, a mistake in this function may cause endless loops as the driver searches through the linked list of ring segments over and over again. Fix a couple bugs that may lead to loops or bad output: 1. Bail out if we get a NULL pointer when translating the segment's private structure and the starting DMA address of the segment chunk. If this happens, we've been handed a starting TRB pointer from a different ring. 2. Make sure the function works when there's multiple segments in the ring. In the while loop to search through the ring segments, use the current segment variable (cur_seg), rather than the starting segment variable (start_seg) that is passed in. 3. Stop searching the ring if we've run through all the segments in the ring. Signed-off-by: Sarah Sharp Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/xhci-ring.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'drivers/usb') diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 173c39c76489..821b7b4709de 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -864,9 +864,11 @@ static struct xhci_segment *trb_in_td( cur_seg = start_seg; do { + if (start_dma == 0) + return 0; /* We may get an event for a Link TRB in the middle of a TD */ end_seg_dma = xhci_trb_virt_to_dma(cur_seg, - &start_seg->trbs[TRBS_PER_SEGMENT - 1]); + &cur_seg->trbs[TRBS_PER_SEGMENT - 1]); /* If the end TRB isn't in this segment, this is set to 0 */ end_trb_dma = xhci_trb_virt_to_dma(cur_seg, end_trb); @@ -893,8 +895,9 @@ static struct xhci_segment *trb_in_td( } cur_seg = cur_seg->next; start_dma = xhci_trb_virt_to_dma(cur_seg, &cur_seg->trbs[0]); - } while (1); + } while (cur_seg != start_seg); + return 0; } /* -- cgit v1.2.1