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    Subject[PATCH v2 02/26] usb: gadget: bdc: remove usage of list iterator past the loop body
    Date
    If the list representing the request queue does not contain the expected
    request, the value of the list_for_each_entry() iterator will not point
    to a valid structure. To avoid type confusion in such case, the list
    iterator scope will be limited to the list_for_each_entry() loop.

    In preparation to limiting scope of the list iterator to the list traversal
    loop, use a dedicated pointer to point to the found request object [1].

    Link: https://lore.kernel.org/all/YhdfEIwI4EdtHdym@kroah.com/
    Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com>
    ---
    drivers/usb/gadget/udc/bdc/bdc_ep.c | 13 +++++++++----
    1 file changed, 9 insertions(+), 4 deletions(-)

    diff --git a/drivers/usb/gadget/udc/bdc/bdc_ep.c b/drivers/usb/gadget/udc/bdc/bdc_ep.c
    index 8e2f20b12519..fa88f210ecd5 100644
    --- a/drivers/usb/gadget/udc/bdc/bdc_ep.c
    +++ b/drivers/usb/gadget/udc/bdc/bdc_ep.c
    @@ -1757,6 +1757,7 @@ static int bdc_gadget_ep_dequeue(struct usb_ep *_ep,
    struct usb_request *_req)
    {
    struct bdc_req *req;
    + struct bdc_req *iter;
    unsigned long flags;
    struct bdc_ep *ep;
    struct bdc *bdc;
    @@ -1771,12 +1772,16 @@ static int bdc_gadget_ep_dequeue(struct usb_ep *_ep,
    dev_dbg(bdc->dev, "%s ep:%s req:%p\n", __func__, ep->name, req);
    bdc_dbg_bd_list(bdc, ep);
    spin_lock_irqsave(&bdc->lock, flags);
    +
    + req = NULL;
    /* make sure it's still queued on this endpoint */
    - list_for_each_entry(req, &ep->queue, queue) {
    - if (&req->usb_req == _req)
    - break;
    + list_for_each_entry(iter, &ep->queue, queue) {
    + if (&iter->usb_req != _req)
    + continue;
    + req = iter;
    + break;
    }
    - if (&req->usb_req != _req) {
    + if (!req) {
    spin_unlock_irqrestore(&bdc->lock, flags);
    dev_err(bdc->dev, "usb_req !=req n");
    return -EINVAL;
    --
    2.25.1
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