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random: print a warning for the first ten uninitialized random users

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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 <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o 2016-06-13 10:10:51 -04:00
parent 3371f3da08
commit 9b4d008787
1 changed files with 8 additions and 4 deletions
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12
drivers/char/random.c
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@ -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 "
"(%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);