apparmor: don't try to replace stale label in ptraceme check

begin_current_label_crit_section() must run in sleepable context because
when label_is_stale() is true, aa_replace_current_label() runs, which uses
prepare_creds(), which can sleep.

Until now, the ptraceme access check (which runs with tasklist_lock held)
violated this rule.

Fixes: b2d09ae449ced ("apparmor: move ptrace checks to using labels")
Reported-by: Cyrill Gorcunov <gorcunov@gmail.com>
Reported-by: kernel test robot <rong.a.chen@intel.com>
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 2c842f24821b..d08aac05c65a 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -132,11 +132,11 @@ static int apparmor_ptrace_traceme(struct task_struct *parent)
         struct aa_label *tracer, *tracee;
         int error;
 
-        tracee = begin_current_label_crit_section();
+        tracee = __begin_current_label_crit_section();
         tracer = aa_get_task_label(parent);
         error = aa_may_ptrace(tracer, tracee, AA_PTRACE_TRACE);
         aa_put_label(tracer);
-        end_current_label_crit_section(tracee);
+        __end_current_label_crit_section(tracee);
 
         return error;
 }