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authorOleg Nesterov <oleg@redhat.com>2013-07-03 15:08:31 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-03 16:08:03 -0700
commit8190773985141f063e1d6dc10200527c655abfb5 (patch)
tree5c148834f047748dfa2ce3500236b89656976567 /include
parent80628ca06c5d42929de6bc22c0a41589a834d151 (diff)
kernel/fork.c:copy_process(): don't add the uninitialized child to thread/task/pid lists
copy_process() adds the new child to thread_group/init_task.tasks list and then does attach_pid(child, PIDTYPE_PID). This means that the lockless next_thread() or next_task() can see this thread with the wrong pid. Say, "ls /proc/pid/task" can list the same inode twice. We could move attach_pid(child, PIDTYPE_PID) up, but in this case find_task_by_vpid() can find the new thread before it was fully initialized. And this is already true for PIDTYPE_PGID/PIDTYPE_SID, With this patch copy_process() initializes child->pids[*].pid first, then calls attach_pid() to insert the task into the pid->tasks list. attach_pid() no longer need the "struct pid*" argument, it is always called after pid_link->pid was already set. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Sergey Dyasly <dserrg@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/pid.h6
1 files changed, 2 insertions, 4 deletions
diff --git a/include/linux/pid.h b/include/linux/pid.h
index a089a3c447fc..23705a53abba 100644
--- a/include/linux/pid.h
+++ b/include/linux/pid.h
@@ -86,11 +86,9 @@ extern struct task_struct *get_pid_task(struct pid *pid, enum pid_type);
extern struct pid *get_task_pid(struct task_struct *task, enum pid_type type);
/*
- * attach_pid() and detach_pid() must be called with the tasklist_lock
- * write-held.
+ * these helpers must be called with the tasklist_lock write-held.
*/
-extern void attach_pid(struct task_struct *task, enum pid_type type,
- struct pid *pid);
+extern void attach_pid(struct task_struct *task, enum pid_type);
extern void detach_pid(struct task_struct *task, enum pid_type);
extern void change_pid(struct task_struct *task, enum pid_type,
struct pid *pid);