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drivers, usb: convert ffs_data.ref from atomic_t to refcount_t 

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 16:21:12 +02:00 committed by Greg Kroah-Hartman
parent a25557f247
commit 43938613c6
2 changed files with 6 additions and 5 deletions
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8
drivers/usb/gadget/function/f_fs.c
View File

@ -1571,14 +1571,14 @@ static void ffs_data_get(struct ffs_data *ffs)
{
ENTER();
atomic_inc(&ffs->ref);
refcount_inc(&ffs->ref);
}
static void ffs_data_opened(struct ffs_data *ffs)
{
ENTER();
atomic_inc(&ffs->ref);
refcount_inc(&ffs->ref);
if (atomic_add_return(1, &ffs->opened) == 1 &&
ffs->state == FFS_DEACTIVATED) {
ffs->state = FFS_CLOSING;
@ -1590,7 +1590,7 @@ static void ffs_data_put(struct ffs_data *ffs)
{
ENTER();
if (unlikely(atomic_dec_and_test(&ffs->ref))) {
if (unlikely(refcount_dec_and_test(&ffs->ref))) {
pr_info("%s(): freeing\n", __func__);
ffs_data_clear(ffs);
BUG_ON(waitqueue_active(&ffs->ev.waitq) ||
@ -1635,7 +1635,7 @@ static struct ffs_data *ffs_data_new(void)
ENTER();
atomic_set(&ffs->ref, 1);
refcount_set(&ffs->ref, 1);
atomic_set(&ffs->opened, 0);
ffs->state = FFS_READ_DESCRIPTORS;
mutex_init(&ffs->mutex);

3
drivers/usb/gadget/function/u_fs.h
View File

@ -20,6 +20,7 @@
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/refcount.h>
#ifdef VERBOSE_DEBUG
#ifndef pr_vdebug
@ -177,7 +178,7 @@ struct ffs_data {
struct completion ep0req_completion; /* P: mutex */
/* reference counter */
atomic_t ref;
refcount_t ref;
/* how many files are opened (EP0 and others) */
atomic_t opened;