Oleg Nesterov wrote:
> Without rcu/tasklist/siglock lock task_pid_nr_ns() may read the freed memory,
> move the callsite under ->siglock.
>
> Sadly, we can report pid == 0 if the task was detached.
>
> Signed-off-by: Oleg Nesterov <[email protected]>
Acked-by: Pavel Emelyanov <[email protected]>
> --- 24/fs/proc/array.c~dtst 2007-11-09 12:57:30.000000000 +0300
> +++ 24/fs/proc/array.c 2007-11-17 21:26:55.000000000 +0300
> @@ -392,7 +392,7 @@ static int do_task_stat(struct task_stru
> sigset_t sigign, sigcatch;
> char state;
> int res;
> - pid_t ppid = 0, pgid = -1, sid = -1;
> + pid_t pid = 0, ppid = 0, pgid = -1, sid = -1;
> int num_threads = 0;
> struct mm_struct *mm;
> unsigned long long start_time;
> @@ -403,9 +403,6 @@ static int do_task_stat(struct task_stru
> unsigned long rsslim = 0;
> char tcomm[sizeof(task->comm)];
> unsigned long flags;
> - struct pid_namespace *ns;
> -
> - ns = current->nsproxy->pid_ns;
>
> state = *get_task_state(task);
> vsize = eip = esp = 0;
> @@ -425,6 +422,7 @@ static int do_task_stat(struct task_stru
>
> rcu_read_lock();
> if (lock_task_sighand(task, &flags)) {
> + struct pid_namespace *ns = current->nsproxy->pid_ns;
> struct signal_struct *sig = task->signal;
>
> if (sig->tty) {
> @@ -461,6 +459,7 @@ static int do_task_stat(struct task_stru
> gtime = cputime_add(gtime, sig->gtime);
> }
>
> + pid = task_pid_nr_ns(task, ns);
> sid = task_session_nr_ns(task, ns);
> pgid = task_pgrp_nr_ns(task, ns);
> ppid = task_ppid_nr_ns(task, ns);
> @@ -495,7 +494,7 @@ static int do_task_stat(struct task_stru
> res = sprintf(buffer, "%d (%s) %c %d %d %d %d %d %u %lu \
> %lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \
> %lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu %lu %ld\n",
> - task_pid_nr_ns(task, ns),
> + pid,
> tcomm,
> state,
> ppid,
>
>
-
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