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drivers, usb: convert dev_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 16:21:13 +02:00 committed by Greg Kroah-Hartman
parent 43938613c6
commit b7ddc981d7
1 changed files with 5 additions and 4 deletions
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9
drivers/usb/gadget/legacy/inode.c
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@ -27,6 +27,7 @@
#include <linux/mmu_context.h>
#include <linux/aio.h>
#include <linux/uio.h>
#include <linux/refcount.h>
#include <linux/device.h>
#include <linux/moduleparam.h>
@ -114,7 +115,7 @@ enum ep0_state {
struct dev_data {
spinlock_t lock;
atomic_t count;
refcount_t count;
enum ep0_state state; /* P: lock */
struct usb_gadgetfs_event event [N_EVENT];
unsigned ev_next;
@ -150,12 +151,12 @@ struct dev_data {
static inline void get_dev (struct dev_data *data)
{
atomic_inc (&data->count);
refcount_inc (&data->count);
}
static void put_dev (struct dev_data *data)
{
if (likely (!atomic_dec_and_test (&data->count)))
if (likely (!refcount_dec_and_test (&data->count)))
return;
/* needs no more cleanup */
BUG_ON (waitqueue_active (&data->wait));
@ -170,7 +171,7 @@ static struct dev_data *dev_new (void)
if (!dev)
return NULL;
dev->state = STATE_DEV_DISABLED;
atomic_set (&dev->count, 1);
refcount_set (&dev->count, 1);
spin_lock_init (&dev->lock);
INIT_LIST_HEAD (&dev->epfiles);
init_waitqueue_head (&dev->wait);