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authorSarah Sharp <sarah.a.sharp@linux.intel.com>2009-11-03 22:02:24 -0800
committerGreg Kroah-Hartman <gregkh@suse.de>2009-11-17 16:46:34 -0800
commit2fa88daa6f299bfb83672c3b525d786ad03b4735 (patch)
tree1b3a7cf0507f2b090a581e14ef9a1261e73225d7
parentd94c05e33d9212ee67b8d4998f984cc71df8168b (diff)
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 <sarah.a.sharp@linux.intel.com> Cc: stable <stable@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/usb/host/xhci-ring.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 173c39c7648..821b7b4709d 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;
}
/*