From: Oleg Nesterov Date: Mon, 14 Jan 2008 21:02:37 +0000 (+0300) Subject: fix the "remove task_ppid_nr_ns" commit X-Git-Tag: v2.6.24-rc8~13 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=a98fdcef941e107eeabae622d85a1f476f25a160;p=linux-2.6-omap-h63xx.git fix the "remove task_ppid_nr_ns" commit Commit 84427eaef1fb91704c7112bdb598c810003b99f3 (remove task_ppid_nr_ns) moved the task_tgid_nr_ns(task->real_parent) outside of lock_task_sighand(). This is wrong, ->real_parent could be freed/reused. Both ->parent/real_parent point to nothing after __exit_signal() because we remove the child from ->children list, and thus the child can't be reparented when its parent exits. rcu_read_lock() protects ->parent/real_parent, but _only_ if we know it was valid before we take rcu lock. Revert this part of the patch. Signed-off-by: Oleg Nesterov Signed-off-by: Linus Torvalds --- diff --git a/fs/proc/array.c b/fs/proc/array.c index 810eb8fd650..eb97f2897e2 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -426,7 +426,6 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole) cgtime = gtime = cputime_zero; rcu_read_lock(); - ppid = task_tgid_nr_ns(task->real_parent, ns); if (lock_task_sighand(task, &flags)) { struct signal_struct *sig = task->signal; @@ -465,6 +464,7 @@ static int do_task_stat(struct task_struct *task, char *buffer, int whole) } sid = task_session_nr_ns(task, ns); + ppid = task_tgid_nr_ns(task->real_parent, ns); pgid = task_pgrp_nr_ns(task, ns); unlock_task_sighand(task, &flags);