lkml.org 
[lkml]   [2012]   [May]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[ 52/91] USB: Remove races in devio.c
    3.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Huajun Li <huajun.li.lee@gmail.com>

    commit 4e09dcf20f7b5358615514c2ec8584b248ab8874 upstream.

    There exist races in devio.c, below is one case,
    and there are similar races in destroy_async()
    and proc_unlinkurb(). Remove these races.

    cancel_bulk_urbs() async_completed()
    ------------------- -----------------------
    spin_unlock(&ps->lock);

    list_move_tail(&as->asynclist,
    &ps->async_completed);

    wake_up(&ps->wait);

    Lead to free_async() be triggered,
    then urb and 'as' will be freed.

    usb_unlink_urb(as->urb);
    ===> refer to the freed 'as'

    Signed-off-by: Huajun Li <huajun.li.lee@gmail.com>
    Cc: Alan Stern <stern@rowland.harvard.edu>
    Cc: Oncaphillis <oncaphillis@snafu.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/usb/core/devio.c | 33 +++++++++++++++++++++++++--------
    1 file changed, 25 insertions(+), 8 deletions(-)

    --- a/drivers/usb/core/devio.c
    +++ b/drivers/usb/core/devio.c
    @@ -333,17 +333,14 @@ static struct async *async_getcompleted(
    static struct async *async_getpending(struct dev_state *ps,
    void __user *userurb)
    {
    - unsigned long flags;
    struct async *as;

    - spin_lock_irqsave(&ps->lock, flags);
    list_for_each_entry(as, &ps->async_pending, asynclist)
    if (as->userurb == userurb) {
    list_del_init(&as->asynclist);
    - spin_unlock_irqrestore(&ps->lock, flags);
    return as;
    }
    - spin_unlock_irqrestore(&ps->lock, flags);
    +
    return NULL;
    }

    @@ -398,6 +395,7 @@ static void cancel_bulk_urbs(struct dev_
    __releases(ps->lock)
    __acquires(ps->lock)
    {
    + struct urb *urb;
    struct async *as;

    /* Mark all the pending URBs that match bulk_addr, up to but not
    @@ -420,8 +418,11 @@ __acquires(ps->lock)
    list_for_each_entry(as, &ps->async_pending, asynclist) {
    if (as->bulk_status == AS_UNLINK) {
    as->bulk_status = 0; /* Only once */
    + urb = as->urb;
    + usb_get_urb(urb);
    spin_unlock(&ps->lock); /* Allow completions */
    - usb_unlink_urb(as->urb);
    + usb_unlink_urb(urb);
    + usb_put_urb(urb);
    spin_lock(&ps->lock);
    goto rescan;
    }
    @@ -472,6 +473,7 @@ static void async_completed(struct urb *

    static void destroy_async(struct dev_state *ps, struct list_head *list)
    {
    + struct urb *urb;
    struct async *as;
    unsigned long flags;

    @@ -479,10 +481,13 @@ static void destroy_async(struct dev_sta
    while (!list_empty(list)) {
    as = list_entry(list->next, struct async, asynclist);
    list_del_init(&as->asynclist);
    + urb = as->urb;
    + usb_get_urb(urb);

    /* drop the spinlock so the completion handler can run */
    spin_unlock_irqrestore(&ps->lock, flags);
    - usb_kill_urb(as->urb);
    + usb_kill_urb(urb);
    + usb_put_urb(urb);
    spin_lock_irqsave(&ps->lock, flags);
    }
    spin_unlock_irqrestore(&ps->lock, flags);
    @@ -1410,12 +1415,24 @@ static int proc_submiturb(struct dev_sta

    static int proc_unlinkurb(struct dev_state *ps, void __user *arg)
    {
    + struct urb *urb;
    struct async *as;
    + unsigned long flags;

    + spin_lock_irqsave(&ps->lock, flags);
    as = async_getpending(ps, arg);
    - if (!as)
    + if (!as) {
    + spin_unlock_irqrestore(&ps->lock, flags);
    return -EINVAL;
    - usb_kill_urb(as->urb);
    + }
    +
    + urb = as->urb;
    + usb_get_urb(urb);
    + spin_unlock_irqrestore(&ps->lock, flags);
    +
    + usb_kill_urb(urb);
    + usb_put_urb(urb);
    +
    return 0;
    }




    \
     
     \ /
      Last update: 2012-05-27 05:01    [W:0.026 / U:29.596 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site