Commit 6071d836 authored May 14, 2009 by Sarah Sharp Committed by Greg Kroah-Hartman Jun 15, 2009

usb; xhci: Fix TRB offset calculations.

Greg KH introduced a bug into xhci_trb_virt_to_dma() when he changed the
type of offset to dma_addr_t from unsigned int and dropped the casts to
unsigned int around the virtual address pointer subtraction.

trb and seg->trbs are both valid pointers to virtual addresses, so the
compiler will mod the subtraction by the size of union trb (16 bytes).
segment_offset is an unsigned long, which is guaranteed to be at least as
big as a void *.

Drop the void * casts in the first if statement because trb and seg->trbs
are both pointers of the same type (pointers to union trb).

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

parent 7dd19e69

drivers/usb/host/xhci-ring.c

+6 −7

Original line number	Diff line number	Diff line
		@@ -74,16 +74,15 @@
		dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg,
		union xhci_trb *trb)
		{
		dma_addr_t offset;
		unsigned long segment_offset;

		if (!seg \|\| !trb \|\| (void ) trb < (void ) seg->trbs)
		if (!seg \|\| !trb \|\| trb < seg->trbs)
		return 0;
		/* offset in bytes, since these are byte-addressable */
		offset = trb - seg->trbs;
		/* SEGMENT_SIZE in bytes, trbs are 16-byte aligned */
		if (offset > SEGMENT_SIZE \|\| (offset % sizeof(*trb)) != 0)
		/* offset in TRBs */
		segment_offset = trb - seg->trbs;
		if (segment_offset > TRBS_PER_SEGMENT)
		return 0;
		return seg->dma + offset;
		return seg->dma + (segment_offset * sizeof(*trb));
		}

		/* Does this link TRB point to the first segment in a ring,