From: Oleg Nesterov <oleg@tv-sign.ru>
To: Andrew Morton <akpm@linux-foundation.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Pavel Emelyanov <xemul@openvz.org>
Cc: linux-kernel@vger.kernel.org
Subject: [PATCH] do_task_stat: don't use task_pid_nr_ns() lockless
Date: Sat, 17 Nov 2007 21:31:09 +0300 [thread overview]
Message-ID: <20071117183109.GA2605@tv-sign.ru> (raw)
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>
--- 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 reply other threads:[~2007-11-17 18:31 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-11-17 18:31 Oleg Nesterov [this message]
2007-11-17 20:11 ` [PATCH] do_task_stat: don't use task_pid_nr_ns() lockless 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
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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