releases/4.4.19/random-print-a-warning-for-the-first-ten-uninitialized-random-users.patch

From 9b4d008787f864f17d008c9c15bbe8a0f7e2fc24 Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Mon, 13 Jun 2016 10:10:51 -0400
Subject: random: print a warning for the first ten uninitialized random users

From: Theodore Ts'o <tytso@mit.edu>

commit 9b4d008787f864f17d008c9c15bbe8a0f7e2fc24 upstream.

Since systemd is consistently using /dev/urandom before it is
initialized, we can't see the other potentially dangerous users of
/dev/urandom immediately after boot.  So print the first ten such
complaints instead.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/char/random.c |   12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1460,12 +1460,16 @@ random_read(struct file *file, char __us
 static ssize_t
 urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
 {
+	static int maxwarn = 10;
 	int ret;
 
-	if (unlikely(nonblocking_pool.initialized == 0))
-		printk_once(KERN_NOTICE "random: %s urandom read "
-			    "with %d bits of entropy available\n",
-			    current->comm, nonblocking_pool.entropy_total);
+	if (unlikely(nonblocking_pool.initialized == 0) &&
+	    maxwarn > 0) {
+		maxwarn--;
+		printk(KERN_NOTICE "random: %s: uninitialized urandom read "
+		       "(%zd bytes read, %d bits of entropy available)\n",
+		       current->comm, nbytes, nonblocking_pool.entropy_total);
+	}
 
 	nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
 	ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);