SELinux: Don't flush inherited SIGKILL during execve()

Don't flush inherited SIGKILL during execve() in SELinux's post cred commit
hook.  This isn't really a security problem: if the SIGKILL came before the
credentials were changed, then we were right to receive it at the time, and
should honour it; if it came after the creds were changed, then we definitely
should honour it; and in any case, all that will happen is that the process
will be scrapped before it ever returns to userspace.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 5 insertions, 4 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index dd19ba81201..5a345115036 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2394,11 +2394,12 @@ static void selinux_bprm_committed_creds(struct linux_binprm *bprm)
                 memset(&itimer, 0, sizeof itimer);
                 for (i = 0; i < 3; i++)
                         do_setitimer(i, &itimer, NULL);
-                flush_signals(current);
                 spin_lock_irq(&current->sighand->siglock);
-                flush_signal_handlers(current, 1);
-                sigemptyset(&current->blocked);
-                recalc_sigpending();
+                if (!(current->signal->flags & SIGNAL_GROUP_EXIT)) {
+                        __flush_signals(current);
+                        flush_signal_handlers(current, 1);
+                        sigemptyset(&current->blocked);
+                }
                 spin_unlock_irq(&current->sighand->siglock);
         }