1 files changed, 19 insertions, 0 deletions

diff --git a/fs/open.c b/fs/open.c
index b5b80469b93d..a59abe3c669a 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -374,6 +374,25 @@ long do_faccessat(int dfd, const char __user *filename, int mode)
                                 override_cred->cap_permitted;
         }
 
+        /*
+         * The new set of credentials can *only* be used in
+         * task-synchronous circumstances, and does not need
+         * RCU freeing, unless somebody then takes a separate
+         * reference to it.
+         *
+         * NOTE! This is _only_ true because this credential
+         * is used purely for override_creds() that installs
+         * it as the subjective cred. Other threads will be
+         * accessing ->real_cred, not the subjective cred.
+         *
+         * If somebody _does_ make a copy of this (using the
+         * 'get_current_cred()' function), that will clear the
+         * non_rcu field, because now that other user may be
+         * expecting RCU freeing. But normal thread-synchronous
+         * cred accesses will keep things non-RCY.
+         */
+        override_cred->non_rcu = 1;
+
         old_cred = override_creds(override_cred);
 retry:
         res = user_path_at(dfd, filename, lookup_flags, &path);