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

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commit 9b4d008787 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>
This commit is contained in:
Theodore Ts'o
2016-06-13 10:10:51 -04:00
committed by popcornmix
parent e623292b74
commit 08d46758aa
1 changed files with 8 additions and 4 deletions
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12
drivers/char/random.c
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@@ -1460,12 +1460,16 @@ random_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
static ssize_t static ssize_t
urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos) urandom_read(struct file *file, char __user *buf, size_t nbytes, loff_t *ppos)
{ {
static int maxwarn = 10;
int ret; int ret;
if (unlikely(nonblocking_pool.initialized == 0)) if (unlikely(nonblocking_pool.initialized == 0) &&
printk_once(KERN_NOTICE "random: %s urandom read " maxwarn > 0) {
"with %d bits of entropy available\n", maxwarn--;
current->comm, nonblocking_pool.entropy_total); 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)); nbytes = min_t(size_t, nbytes, INT_MAX >> (ENTROPY_SHIFT + 3));
ret = extract_entropy_user(&nonblocking_pool, buf, nbytes); ret = extract_entropy_user(&nonblocking_pool, buf, nbytes);