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authorElena Reshetova <elena.reshetova@intel.com>2017-10-20 13:26:02 +0300
committerJan Kara <jack@suse.cz>2017-10-31 17:54:56 +0100
commitab97f87325e28b7ef7717e6cb62e8da14a7176e1 (patch)
tree7ce8f0a747efaff1907f3774479dcbc2f4762c48 /kernel/audit_tree.c
parent6685df31255493c3f0e9e0b8bf885e4c9762fc5d (diff)
fsnotify: convert fsnotify_mark.refcnt from atomic_t to refcount_t
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable fsnotify_mark.refcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Jan Kara <jack@suse.cz>
Diffstat (limited to 'kernel/audit_tree.c')
-rw-r--r--kernel/audit_tree.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index 011d46e5f73f..45ec960ad536 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -1007,7 +1007,7 @@ static void audit_tree_freeing_mark(struct fsnotify_mark *entry, struct fsnotify
* We are guaranteed to have at least one reference to the mark from
* either the inode or the caller of fsnotify_destroy_mark().
*/
- BUG_ON(atomic_read(&entry->refcnt) < 1);
+ BUG_ON(refcount_read(&entry->refcnt) < 1);
}
static const struct fsnotify_ops audit_tree_ops = {