From: Pavel Emelyanov <xemul@openvz.org>
To: Oleg Nesterov <oleg@tv-sign.ru>,
Andrew Morton <akpm@linux-foundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
Pavel Emelyanov <xemul@openvz.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] do_task_stat: don't use task_pid_nr_ns() lockless
Date: Mon, 19 Nov 2007 12:31:59 +0300 [thread overview]
Message-ID: <4741580F.7070301@openvz.org> (raw)
In-Reply-To: <20071117183109.GA2605@tv-sign.ru>
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 <oleg@tv-sign.ru>
Acked-by: Pavel Emelyanov <xemul@openvz.org>
> --- 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,
>
>
next prev parent reply other threads:[~2007-11-19 9:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-17 18:31 [PATCH] do_task_stat: don't use task_pid_nr_ns() lockless Oleg Nesterov
2007-11-17 20:11 ` Eric W. Biederman
2007-11-19 9:30 ` Pavel Emelyanov
2007-11-19 18:04 ` Eric W. Biederman
2007-11-19 9:31 ` Pavel Emelyanov [this message]
2007-11-19 21:59 ` [PATCH 0/4] proc: Cleanup status files Eric W. Biederman
2007-11-19 22:04 ` [PATCH 1/4] proc: Implement proc_single_file_operations Eric W. Biederman
2007-11-19 22:06 ` [PATCH 2/4] proc: Rewrite do_task_stat to correctly handle pid namespaces Eric W. Biederman
2007-11-19 22:10 ` [PATCH 3/4] proc: seqfile convert proc_pid_status to properly " Eric W. Biederman
2007-11-19 22:13 ` [PATCH] proc: seqfile convert proc_pid_statm Eric W. Biederman
2007-11-20 10:34 ` [PATCH 0/4] proc: Cleanup status files Pavel Emelyanov
2007-11-19 22:30 ` [PATCH] proc: Proper pidns handling for /proc/self Eric W. Biederman
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