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authorOleg Nesterov <oleg@redhat.com>2017-08-21 17:35:02 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-08-24 17:02:36 -0700
commitb4cf49024cf412a94121e61f8056636c557ead98 (patch)
tree38a9cdf76224f841d41faff29b57a51a90e6c3c4 /include
parent46d51a26efbc7cbaa2bc1f01628a00a604193856 (diff)
pids: make task_tgid_nr_ns() safe
commit dd1c1f2f2028a7b851f701fc6a8ebe39dcb95e7c upstream. This was reported many times, and this was even mentioned in commit 52ee2dfdd4f5 ("pids: refactor vnr/nr_ns helpers to make them safe") but somehow nobody bothered to fix the obvious problem: task_tgid_nr_ns() is not safe because task->group_leader points to nowhere after the exiting task passes exit_notify(), rcu_read_lock() can not help. We really need to change __unhash_process() to nullify group_leader, parent, and real_parent, but this needs some cleanups. Until then we can turn task_tgid_nr_ns() into another user of __task_pid_nr_ns() and fix the problem. Reported-by: Troy Kensinger <tkensinger@google.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/pid.h4
-rw-r--r--include/linux/sched.h50
2 files changed, 30 insertions, 24 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h
index 23705a53abba..97b745ddece5 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -8,7 +8,9 @@ enum pid_type
PIDTYPE_PID,
PIDTYPE_PGID,
PIDTYPE_SID,
- PIDTYPE_MAX
+ PIDTYPE_MAX,
+ /* only valid to __task_pid_nr_ns() */
+ __PIDTYPE_TGID
};
/*
diff --git a/include/linux/sched.h b/include/linux/sched.h
index eff7c1fad26f..e887c8d6f395 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1949,31 +1949,8 @@ static inline pid_t task_tgid_nr(struct task_struct *tsk)
return tsk->tgid;
}
-pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);
-
-static inline pid_t task_tgid_vnr(struct task_struct *tsk)
-{
- return pid_vnr(task_tgid(tsk));
-}
-
static inline int pid_alive(const struct task_struct *p);
-static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)
-{
- pid_t pid = 0;
-
- rcu_read_lock();
- if (pid_alive(tsk))
- pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
- rcu_read_unlock();
-
- return pid;
-}
-
-static inline pid_t task_ppid_nr(const struct task_struct *tsk)
-{
- return task_ppid_nr_ns(tsk, &init_pid_ns);
-}
static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
struct pid_namespace *ns)
@@ -1998,6 +1975,33 @@ static inline pid_t task_session_vnr(struct task_struct *tsk)
return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);
}
+static inline pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns)
+{
+ return __task_pid_nr_ns(tsk, __PIDTYPE_TGID, ns);
+}
+
+static inline pid_t task_tgid_vnr(struct task_struct *tsk)
+{
+ return __task_pid_nr_ns(tsk, __PIDTYPE_TGID, NULL);
+}
+
+static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)
+{
+ pid_t pid = 0;
+
+ rcu_read_lock();
+ if (pid_alive(tsk))
+ pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
+ rcu_read_unlock();
+
+ return pid;
+}
+
+static inline pid_t task_ppid_nr(const struct task_struct *tsk)
+{
+ return task_ppid_nr_ns(tsk, &init_pid_ns);
+}
+
/* obsolete, do not use */
static inline pid_t task_pgrp_nr(struct task_struct *tsk)
{