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authorOleg Nesterov <oleg@redhat.com>2010-04-01 15:13:57 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2010-04-01 08:50:21 -0700
commitb95c35e76b29ba812e5dabdd91592e25ec640e93 (patch)
tree9584cf21e47baec986f5dc5455081e8538126be1
parent30d1872d9eb3663b4cf7bdebcbf5cd465674cced (diff)
oom: fix the unsafe usage of badness() in proc_oom_score()
proc_oom_score(task) has a reference to task_struct, but that is all. If this task was already released before we take tasklist_lock - we can't use task->group_leader, it points to nowhere - it is not safe to call badness() even if this task is ->group_leader, has_intersects_mems_allowed() assumes it is safe to iterate over ->thread_group list. - even worse, badness() can hit ->signal == NULL Add the pid_alive() check to ensure __unhash_process() was not called. Also, use "task" instead of task->group_leader. badness() should return the same result for any sub-thread. Currently this is not true, but this should be changed anyway. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/proc/base.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index a7310841c83..b1f6e62773d 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -442,12 +442,13 @@ static const struct file_operations proc_lstats_operations = {
unsigned long badness(struct task_struct *p, unsigned long uptime);
static int proc_oom_score(struct task_struct *task, char *buffer)
{
- unsigned long points;
+ unsigned long points = 0;
struct timespec uptime;
do_posix_clock_monotonic_gettime(&uptime);
read_lock(&tasklist_lock);
- points = badness(task->group_leader, uptime.tv_sec);
+ if (pid_alive(task))
+ points = badness(task, uptime.tv_sec);
read_unlock(&tasklist_lock);
return sprintf(buffer, "%lu\n", points);
}