Messages in this thread Patch in this message | | | Date | Tue, 15 Jan 2008 00:02:37 +0300 | From | Oleg Nesterov <> | Subject | [PATCH] fix the "remove task_ppid_nr_ns" commit |
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The commit 84427eaef1fb91704c7112bdb598c810003b99f3 (remove task_ppid_nr_ns) moves 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 nothnig 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 <oleg@tv-sign.ru>
--- t/fs/proc/array.c~ppid_fix 2008-01-14 23:45:35.000000000 +0300 +++ t/fs/proc/array.c 2008-01-14 23:59:27.000000000 +0300 @@ -426,7 +426,6 @@ static int do_task_stat(struct task_stru 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_stru } 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);
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