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

[ Upstream commit ca3fde5214e1d24f78269b337d3f22afd6bf445e ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 4f08023101f3cd938b55e11bd05fc1d95c88dfcd..1c6b389ad8f945e1d55f2e875b4fe8d0dc693f24 100644 (file)
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c
@@ -123,11 +123,11 @@ 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;
 }