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@xxxxxxxxx>
Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
---
fs/notify/group.c | 6 +++---
include/linux/fsnotify_backend.h | 3 ++-
2 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/fs/notify/group.c b/fs/notify/group.c
index fbe3cbe..81356c1 100644
--- a/fs/notify/group.c
+++ b/fs/notify/group.c
@@ -98,7 +98,7 @@ void fsnotify_destroy_group(struct fsnotify_group *group)
*/
void fsnotify_get_group(struct fsnotify_group *group)
{
- atomic_inc(&group->refcnt);
+ refcount_inc(&group->refcnt);
}
/*
@@ -106,7 +106,7 @@ void fsnotify_get_group(struct fsnotify_group *group)
*/
void fsnotify_put_group(struct fsnotify_group *group)
{
- if (atomic_dec_and_test(&group->refcnt))
+ if (refcount_dec_and_test(&group->refcnt))
fsnotify_final_destroy_group(group);
}
@@ -122,7 +122,7 @@ struct fsnotify_group *fsnotify_alloc_group(const struct fsnotify_ops *ops)
return ERR_PTR(-ENOMEM);
/* set to 0 when there a no external references to this group */
- atomic_set(&group->refcnt, 1);
+ refcount_set(&group->refcnt, 1);
atomic_set(&group->num_marks, 0);
spin_lock_init(&group->notification_lock);
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index e6e689b..1f7aa16 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -17,6 +17,7 @@
#include <linux/types.h>
#include <linux/atomic.h>
#include <linux/user_namespace.h>
+#include <linux/refcount.h>
/*
* IN_* from inotfy.h lines up EXACTLY with FS_*, this is so we can easily
@@ -131,7 +132,7 @@ struct fsnotify_group {
* inotify_init() and the refcnt will hit 0 only when that fd has been
* closed.
*/
- atomic_t refcnt; /* things with interest in this group */
+ refcount_t refcnt; /* things with interest in this group */
const struct fsnotify_ops *ops; /* how this group handles things */
--
2.7.4
--
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