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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: b2d09ae449 ("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>
This commit is contained in:
Jann Horn 2018-09-29 03:49:26 +02:00 committed by John Johansen
parent 0fb871cc42
commit ca3fde5214
1 changed files with 2 additions and 2 deletions
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4
security/apparmor/lsm.c
View File

@ -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;
}