[005/139] oom: fix the unsafe usage of badness() in proc_oom_score()
in [Kernel]
|
Prev: [003/139] drm: remove the EDID blob stored in the EDID property when it is disconnected
Next: 1832-Staging-comedi-add-missing-KERN_INFO-in-ni_at_ao.c.patch
From: Greg KH on 22 Apr 2010 16:40 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: Oleg Nesterov <oleg(a)redhat.com> 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(a)redhat.com> Signed-off-by: Linus Torvalds <torvalds(a)linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de> --- fs/proc/base.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -442,12 +442,13 @@ static const struct file_operations proc 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |