Alan Stern wrote:
> On Mon, 1 Mar 2010, Clemens Ladisch wrote:
> > The EHCI driver stores in usb_host_endpoint.hcpriv a pointer to either
> > an ehci_qh or an ehci_iso_stream structure, and uses the contents of the
> > hw_info1 field to distinguish the two cases.
> >
> > After ehci_qh was split into hw and sw parts, ehci_iso_stream must also
> > be adjusted so that it again looks like an ehci_qh structure.
> > ...
> > --- linux/drivers/usb/host/ehci-sched.c
> > +++ linux/drivers/usb/host/ehci-sched.c
> > @@ -932,6 +932,7 @@ iso_stream_alloc (gfp_t mem_flags)
> > INIT_LIST_HEAD(&stream->free_list);
> > stream->next_uframe = -1;
> > stream->refcount = 1;
> > + stream->fake_hw = (struct ehci_qh_hw *)&stream->fake_qh_hw;
>
> This is silly. It's ridiculous to allocate two unused words in every
> ehci_iso_stream structure just to have something to point at. Why not
> instead replace the test for qh->hw->hw_info1 == 0 with a test for
> qh->hw == NULL?
[PATCH] USB: EHCI: adjust ehci_iso_stream for changes in ehci_qh
The EHCI driver stores in usb_host_endpoint.hcpriv a pointer to either
an ehci_qh or an ehci_iso_stream structure, and uses the contents of the
hw_info1 field to distinguish the two cases.
After ehci_qh was split into hw and sw parts, ehci_iso_stream must also
be adjusted so that it again looks like an ehci_qh structure.
This fixes a NULL pointer access in ehci_endpoint_disable() when it
tries to access qh->hw->hw_info1.
Signed-off-by: Clemens Ladisch <clemens@xxxxxxxxxx>
Reported-by: Colin Fletcher <colin.m.fletcher@xxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxx>
---
drivers/usb/host/ehci-hcd.c | 2 +-
drivers/usb/host/ehci-sched.c | 4 ++--
drivers/usb/host/ehci.h | 5 ++---
3 files changed, 5 insertions(+), 6 deletions(-)
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -394,9 +394,8 @@ struct ehci_iso_sched {
* acts like a qh would, if EHCI had them for ISO.
*/
struct ehci_iso_stream {
- /* first two fields match QH, but info1 == 0 */
- __hc32 hw_next;
- __hc32 hw_info1;
+ /* first field matches ehci_hq, but is NULL */
+ struct ehci_qh_hw *hw;
u32 refcount;
u8 bEndpointAddress;
--- a/drivers/usb/host/ehci-hcd.c
+++ b/drivers/usb/host/ehci-hcd.c
@@ -995,7 +995,7 @@ rescan:
/* endpoints can be iso streams. for now, we don't
* accelerate iso completions ... so spin a while.
*/
- if (qh->hw->hw_info1 == 0) {
+ if (qh->hw == NULL) {
ehci_vdbg (ehci, "iso delay\n");
goto idle_timeout;
}
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -1121,8 +1121,8 @@ iso_stream_find (struct ehci_hcd *ehci, struct urb *urb)
urb->interval);
}
- /* if dev->ep [epnum] is a QH, info1.maxpacket is nonzero */
- } else if (unlikely (stream->hw_info1 != 0)) {
+ /* if dev->ep [epnum] is a QH, hw is set */
+ } else if (unlikely (stream->hw != NULL)) {
ehci_dbg (ehci, "dev %s ep%d%s, not iso??\n",
urb->dev->devpath, epnum,
usb_pipein(urb->pipe) ? "in" : "out");
--
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