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| author | Oleg Nesterov <oleg@redhat.com> | 2010-04-01 15:13:57 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-04-26 07:47:46 -0700 |
| commit | 1628711eab4c0e5b82416b609e38e67a92006c13 (patch) | |
| tree | 5ec9200be42715ba3c4a6c94cfbc81086a89f642 /fs | |
| parent | 898b5ece63b796443073f505a4403a35906f1b0b (diff) | |
| download | kernel-crypto-1628711eab4c0e5b82416b609e38e67a92006c13.tar.gz kernel-crypto-1628711eab4c0e5b82416b609e38e67a92006c13.tar.xz kernel-crypto-1628711eab4c0e5b82416b609e38e67a92006c13.zip | |
oom: fix the unsafe usage of badness() in proc_oom_score()
commit b95c35e76b29ba812e5dabdd91592e25ec640e93 upstream.
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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/proc/base.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 58324c29916..3cd449d2335 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); } |