'kill sig -1' must only apply to caller's namespace

Currently "kill <sig> -1" kills processes in all namespaces and breaks the
isolation of namespaces.  Earlier attempt to fix this was discussed at:

	http://lkml.org/lkml/2008/7/23/148

As suggested by Oleg Nesterov in that thread, use "task_pid_vnr() > 1"
check since task_pid_vnr() returns 0 if process is outside the caller's
namespace.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Tested-by: Daniel Hokka Zakrisson <daniel@hozac.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/signal.c b/kernel/signal.c
index 105217da5c82..4530fc654455 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1144,7 +1144,8 @@ static int kill_something_info(int sig, struct siginfo *info, pid_t pid)
                 struct task_struct * p;
 
                 for_each_process(p) {
-                        if (p->pid > 1 && !same_thread_group(p, current)) {
+                        if (task_pid_vnr(p) > 1 &&
+                                        !same_thread_group(p, current)) {
                                 int err = group_send_sig_info(sig, info, p);
                                 ++count;
                                 if (err != -EPERM)