[PATCH] bacct_add_tsk: fix unsafe and wrong parent/group_leader dereference

[linux-2.6-omap-h63xx.git] / kernel / tsacct.c

diff --git a/kernel/tsacct.c b/kernel/tsacct.c
index db443221ba5ba0038ee3bd40270f6b5a2a8922b7..65a5036a3d9519031526f499c5495ac23401a90e 100644 (file)
--- a/kernel/tsacct.c
+++ b/kernel/tsacct.c
@@ -36,7 +36,7 @@ void bacct_add_tsk(struct taskstats *stats, struct task_struct *tsk)
 
        /* calculate task elapsed time in timespec */
        do_posix_clock_monotonic_gettime(&uptime);
-       ts = timespec_sub(uptime, current->group_leader->start_time);
+       ts = timespec_sub(uptime, tsk->start_time);
        /* rebase elapsed time to usec */
        ac_etime = timespec_to_ns(&ts);
        do_div(ac_etime, NSEC_PER_USEC);
@@ -58,7 +58,10 @@ void bacct_add_tsk(struct taskstats *stats, struct task_struct *tsk)
        stats->ac_uid    = tsk->uid;
        stats->ac_gid    = tsk->gid;
        stats->ac_pid    = tsk->pid;
-       stats->ac_ppid   = (tsk->parent) ? tsk->parent->pid : 0;
+       rcu_read_lock();
+       stats->ac_ppid   = pid_alive(tsk) ?
+                               rcu_dereference(tsk->real_parent)->tgid : 0;
+       rcu_read_unlock();
        stats->ac_utime  = cputime_to_msecs(tsk->utime) * USEC_PER_MSEC;
        stats->ac_stime  = cputime_to_msecs(tsk->stime) * USEC_PER_MSEC;
        stats->ac_minflt = tsk->min_flt;