security, keys: convert key.usage 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>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index c91e4e0..3d95f7d 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -1033,7 +1033,7 @@ struct key *find_keyring_by_name(const char *name, bool skip_perm_check)
/* we've got a match but we might end up racing with
* key_cleanup() if the keyring is currently 'dead'
* (ie. it has a zero usage count) */
- if (!atomic_inc_not_zero(&keyring->usage))
+ if (!refcount_inc_not_zero(&keyring->usage))
continue;
keyring->last_used_at = current_kernel_time().tv_sec;
goto out;
@@ -1250,14 +1250,14 @@ int key_link(struct key *keyring, struct key *key)
struct assoc_array_edit *edit;
int ret;
- kenter("{%d,%d}", keyring->serial, atomic_read(&keyring->usage));
+ kenter("{%d,%d}", keyring->serial, refcount_read(&keyring->usage));
key_check(keyring);
key_check(key);
ret = __key_link_begin(keyring, &key->index_key, &edit);
if (ret == 0) {
- kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage));
+ kdebug("begun {%d,%d}", keyring->serial, refcount_read(&keyring->usage));
ret = __key_link_check_restriction(keyring, key);
if (ret == 0)
ret = __key_link_check_live_key(keyring, key);
@@ -1266,7 +1266,7 @@ int key_link(struct key *keyring, struct key *key)
__key_link_end(keyring, &key->index_key, edit);
}
- kleave(" = %d {%d,%d}", ret, keyring->serial, atomic_read(&keyring->usage));
+ kleave(" = %d {%d,%d}", ret, keyring->serial, refcount_read(&keyring->usage));
return ret;
}
EXPORT_SYMBOL(key_link);
