futex: Prevent attaching to kernel threads

[firefly-linux-kernel-4.4.55.git] / kernel / futex.c

diff --git a/kernel/futex.c b/kernel/futex.c
index 7c68225e3967c075d943b179c276056cdb807dbc..81dbe773ce4c20bdeafa8effa858cf85b995dfbe 100644 (file)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -814,6 +814,11 @@ lookup_pi_state(u32 uval, struct futex_hash_bucket *hb,
        if (!p)
                return -ESRCH;
 
+       if (!p->mm) {
+               put_task_struct(p);
+               return -EPERM;
+       }
+
        /*
         * We need to look at the task state flags to figure out,
         * whether the task is exiting. To protect against the do_exit