Set cred->user_ns in key_replace_session_keyring

Since this cred was not created with copy_creds(), it needs to get
initialized.  Otherwise use of syscall(__NR_keyctl, KEYCTL_SESSION_TO_PARENT);
can lead to a NULL deref.  Thanks to Robert for finding this.

But introduced by commit 47a150edc2a ("Cache user_ns in struct cred").

Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Reported-by: Robert Święcki <robert@swiecki.net>
Cc: David Howells <dhowells@redhat.com>
Cc: stable@kernel.org (2.6.39)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 6c0480db8885..a3063eb3dc23 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -847,6 +847,7 @@ void key_replace_session_keyring(void)
         new-> sgid      = old-> sgid;
         new->fsgid      = old->fsgid;
         new->user       = get_uid(old->user);
+        new->user_ns    = new->user->user_ns;
         new->group_info = get_group_info(old->group_info);
 
         new->securebits = old->securebits;