CRED: Fix commit_creds() on a process that has no mm

Fix commit_creds()'s handling of a process that has no mm (such as one that is
calling or has called daemonize()).  commit_creds() should check to see if
task->mm is not NULL before calling set_dumpable() on it.

Reported-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/cred.c b/kernel/cred.c
index ff7bc071991c..480a61aec805 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -372,7 +372,8 @@ int commit_creds(struct cred *new)
             old->fsuid != new->fsuid ||
             old->fsgid != new->fsgid ||
             !cap_issubset(new->cap_permitted, old->cap_permitted)) {
-                set_dumpable(task->mm, suid_dumpable);
+                if (task->mm)
+                        set_dumpable(task->mm, suid_dumpable);
                 task->pdeath_signal = 0;
                 smp_wmb();
         }