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drivers, usb: convert ep_data.count from atomic_t to refcount_t

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refcount_t type and corresponding API should be
used instead of atomic_t when the variable is used as
a reference counter. This allows to avoid accidental
refcounter overflows that might lead to use-after-free
situations.

Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Elena Reshetova 2017-03-06 16:21:14 +02:00 committed by Greg Kroah-Hartman
parent b7ddc981d7
commit 8d66db50b2
1 changed files with 4 additions and 4 deletions
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8
drivers/usb/gadget/legacy/inode.c
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@ -191,7 +191,7 @@ enum ep_state {
struct ep_data {
struct mutex lock;
enum ep_state state;
atomic_t count;
refcount_t count;
struct dev_data *dev;
/* must hold dev->lock before accessing ep or req */
struct usb_ep *ep;
@ -206,12 +206,12 @@ struct ep_data {
static inline void get_ep (struct ep_data *data)
{
atomic_inc (&data->count);
refcount_inc (&data->count);
}
static void put_ep (struct ep_data *data)
{
if (likely (!atomic_dec_and_test (&data->count)))
if (likely (!refcount_dec_and_test (&data->count)))
return;
put_dev (data->dev);
/* needs no more cleanup */
@ -1562,7 +1562,7 @@ static int activate_ep_files (struct dev_data *dev)
init_waitqueue_head (&data->wait);
strncpy (data->name, ep->name, sizeof (data->name) - 1);
atomic_set (&data->count, 1);
refcount_set (&data->count, 1);
data->dev = dev;
get_dev (dev);