[PATCH 2/2] signals: replace p->pid == 1 check with a check for task_child_reaper

[Daniel Hokka Zakrisson]

p->pid == 1 is insufficient when there are multiple pid namespaces.
Instead, check whether the task is in the current task's
child reaper's thread group.

Signed-off-by: Daniel Hokka Zakrisson <daniel at hozac.com>

diff --git a/kernel/signal.c b/kernel/signal.c
index 93713a5..be932b9 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1142,10 +1142,20 @@ static int kill_something_info(int sig, struct 
siginfo *info, int pid)
  				pid ? find_vpid(-pid) : task_pgrp(current));
  	} else {
  		int retval = 0, count = 0;
-		struct task_struct * p;
+		struct task_struct *p, *reaper = task_child_reaper(current);
+
+		/*
+		 * The reaper has died, so there's probably a
+		 * SIGKILL pending. Return.
+		 */
+		if (unlikely(!reaper)) {
+			ret = -ESRCH;
+			goto out;
+		}

  		for_each_process(p) {
-			if (p->pid > 1 && !same_thread_group(p, current) &&
+			if (!same_thread_group(p, reaper) &&
+			    !same_thread_group(p, current) &&
  			    task_in_pid_ns(p, current->nsproxy->pid_ns)) {
  				int err = group_send_sig_info(sig, info, p);
  				++count;
@@ -1155,6 +1165,7 @@ static int kill_something_info(int sig, struct 
siginfo *info, int pid)
  		}
  		ret = count ? retval : -ESRCH;
  	}
+out:
  	read_unlock(&tasklist_lock);

  	return ret;
-- 
1.5.5.1