path: root/kernel/sched
diff options
authorEric W. Biederman <ebiederm@xmission.com>2012-07-26 05:05:21 -0700
committerEric W. Biederman <ebiederm@xmission.com>2012-11-20 04:17:44 -0800
commit4c44aaafa8108f584831850ab48a975e971db2de (patch)
treec86f225e8256d28271acf3ea8926e70358f3e5c1 /kernel/sched
parentbcf58e725ddc45d31addbc6627d4f0edccc824c1 (diff)
userns: Kill task_user_ns
The task_user_ns function hides the fact that it is getting the user namespace from struct cred on the task. struct cred may go away as soon as the rcu lock is released. This leads to a race where we can dereference a stale user namespace pointer. To make it obvious a struct cred is involved kill task_user_ns. To kill the race modify the users of task_user_ns to only reference the user namespace while the rcu lock is held. Cc: Kees Cook <keescook@chromium.org> Cc: James Morris <james.l.morris@oracle.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/sched')
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 2d8927fda71..2f5eb1838b3 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4029,8 +4029,14 @@ long sched_setaffinity(pid_t pid, const struct cpumask *in_mask)
goto out_free_cpus_allowed;
retval = -EPERM;
- if (!check_same_owner(p) && !ns_capable(task_user_ns(p), CAP_SYS_NICE))
- goto out_unlock;
+ if (!check_same_owner(p)) {
+ rcu_read_lock();
+ if (!ns_capable(__task_cred(p)->user_ns, CAP_SYS_NICE)) {
+ rcu_read_unlock();
+ goto out_unlock;
+ }
+ rcu_read_unlock();
+ }
retval = security_task_setscheduler(p);
if (retval)