Gitweb: http://git.kernel.org/linus/2ae448efc87df6d328f5835969076c7f9fce59c3
Commit: 2ae448efc87df6d328f5835969076c7f9fce59c3
Parent: 6dda81f4384b94930826eded254d8c16f89a9248
Author: Oleg Nesterov <oleg@redhat.com>
AuthorDate: Thu Apr 2 16:58:36 2009 -0700
Committer: Linus Torvalds <torvalds@linux-foundation.org>
CommitDate: Thu Apr 2 19:05:02 2009 -0700
pids: improve get_task_pid() to fix the unsafe sys_wait4()->task_pgrp()
sys_wait4() does get_pid(task_pgrp(current)), this is not safe. We can
add rcu lock/unlock around, but we already have get_task_pid() which can
be improved to handle the special pids in more reliable manner.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/exit.c | 2 +-
kernel/pid.c | 2 ++
2 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index 029415d..384f09c 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -1737,7 +1737,7 @@ SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
pid = find_get_pid(-upid);
} else if (upid == 0) {
type = PIDTYPE_PGID;
- pid = get_pid(task_pgrp(current));
+ pid = get_task_pid(current, PIDTYPE_PGID);
} else /* upid > 0 */ {
type = PIDTYPE_PID;
pid = find_get_pid(upid);
diff --git a/kernel/pid.c b/kernel/pid.c
index 1b3586f..6628abc 100644
--- a/kernel/pid.c
+++ b/kernel/pid.c
@@ -403,6 +403,8 @@ struct pid *get_task_pid(struct task_struct *task, enum pid_type type)
{
struct pid *pid;
rcu_read_lock();
+ if (type != PIDTYPE_PID)
+ task = task->group_leader;
pid = get_pid(task->pids[type].pid);
rcu_read_unlock();
return pid;
--
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