SELinux: clear parent death signal on SID transitions

Clear parent death signal on SID transitions to prevent unauthorized
signaling between SIDs.

Signed-off-by:  Stephen Smalley <sds@tycho.nsa.gov>
Acked-by: Eric Paris <eparis@parisplace.org>
Signed-off-by: James Morris <jmorris@localhost.localdomain>

1 files changed, 3 insertions, 0 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index d8bc4172819c..36946629b6ca 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1907,6 +1907,9 @@ static void selinux_bprm_post_apply_creds(struct linux_binprm *bprm)
                 spin_unlock_irq(&current->sighand->siglock);
         }
 
+        /* Always clear parent death signal on SID transitions. */
+        current->pdeath_signal = 0;
+
         /* Check whether the new SID can inherit resource limits
            from the old SID.  If not, reset all soft limits to
            the lower of the current task's hard limit and the init