From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Ts'o Subject: [PATCH 2/7] random: print a warning for the first ten uninitialized random users Date: Mon, 13 Jun 2016 11:48:34 -0400 Message-ID: <1465832919-11316-3-git-send-email-tytso@mit.edu> References: <1465832919-11316-1-git-send-email-tytso@mit.edu> Cc: linux-crypto@vger.kernel.org, smueller@chronox.de, herbert@gondor.apana.org.au, andi@firstfloor.org, sandyinchina@gmail.com, jsd@av8n.com, hpa@zytor.com, Theodore Ts'o , stable@kernel.org To: Linux Kernel Developers List Return-path: Received: from imap.thunk.org ([74.207.234.97]:45062 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1424453AbcFMPt2 (ORCPT ); Mon, 13 Jun 2016 11:49:28 -0400 In-Reply-To: <1465832919-11316-1-git-send-email-tytso@mit.edu> Sender: linux-crypto-owner@vger.kernel.org List-ID: 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. Cc: stable@kernel.org Signed-off-by: Theodore Ts'o --- drivers/char/random.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 4e2627a..74596d3 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1458,12 +1458,16 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) 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 " + "(%d 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); -- 2.5.0