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    SubjectRe: [PATCH] USB: don't read past config->interface[] if usb_control_msg() fails in usb_reset_configuration()
    After the loop `for (i = 0; i < config->desc.bNumInterfaces; i++)' if no
    break occurred, i equals config->desc.bNumInterfaces. so if
    usb_control_msg() failed then after goto reset_old_alts we read from
    config->interface[config->desc.bNumInterfaces].

    Reported-by: "Juha Leppanen" <juha_motorsportcom@luukku.com>
    Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
    ---

    >> You correctly identified a problem, but your fix is wrong -- or at
    >> least, it is much too complicated. The proper fix goes like this:
    >
    > /* If not, reinstate the old alternate settings */
    > if (retval < 0) {
    > reset_old_alts:
    > - for (; i >= 0; i--) {
    > + for (i--; i >= 0; i--) {
    > struct usb_interface *intf = config->interface[i];
    > struct usb_host_interface *alt;


    Are you really sure this is better? If usb_hcd_alloc_bandwidth() fails,
    in the loop _before_ the reset_old_alts label, don't we still have to
    reinstate the old alternate settings for that usb_interface
    config->interface[i]? This was what my initial patch tried to do.

    Alternatively usb_hcd_alloc_bandwidth() could undo what it does if an
    error occurs there, then I think i could be decremented.

    IOW isn't this the proper fix?

    Roel

    diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
    index 9bc95fe..4327eab 100644
    --- a/drivers/usb/core/message.c
    +++ b/drivers/usb/core/message.c
    @@ -1489,8 +1489,10 @@ reset_old_alts:
    USB_REQ_SET_CONFIGURATION, 0,
    config->desc.bConfigurationValue, 0,
    NULL, 0, USB_CTRL_SET_TIMEOUT);
    - if (retval < 0)
    + if (retval < 0) {
    + i--;
    goto reset_old_alts;
    + }
    mutex_unlock(&hcd->bandwidth_mutex);

    /* re-init hc/hcd interface/endpoint state */

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      Last update: 2010-02-09 22:57    [W:0.026 / U:96.912 seconds]
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