1 files changed, 18 insertions, 0 deletions

diff --git a/kernel/cred.c b/kernel/cred.c
index d7f7a01082eb..70bda79fae24 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -782,6 +782,24 @@ EXPORT_SYMBOL(set_create_files_as);
 
 #ifdef CONFIG_DEBUG_CREDENTIALS
 
+bool creds_are_invalid(const struct cred *cred)
+{
+        if (cred->magic != CRED_MAGIC)
+                return true;
+        if (atomic_read(&cred->usage) < atomic_read(&cred->subscribers))
+                return true;
+#ifdef CONFIG_SECURITY_SELINUX
+        if (selinux_is_enabled()) {
+                if ((unsigned long) cred->security < PAGE_SIZE)
+                        return true;
+                if ((*(u32 *)cred->security & 0xffffff00) ==
+                    (POISON_FREE << 24 | POISON_FREE << 16 | POISON_FREE << 8))
+                        return true;
+        }
+#endif
+        return false;
+}
+
 /*
  * dump invalid credentials
  */