Messages in this thread Patch in this message | | | Date | Sat, 17 Nov 2007 21:31:09 +0300 | From | Oleg Nesterov <> | Subject | [PATCH] do_task_stat: don't use task_pid_nr_ns() lockless |
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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, - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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