SELinux: clear parent death signal on SID transitions

commit 4ac212ad4e8fafc22fa147fc255ff5fa5435cf33 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index ad8dd4e8657e5487bd7668328238c166248176da..1ee7ca9ed5754e089e32e6f4039cc8119bf87723 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1906,6 +1906,9 @@ 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