Commit 042e293e authored by Jason A. Donenfeld's avatar Jason A. Donenfeld
Browse files

random: wake up /dev/random writers after zap 



When account() is called, and the amount of entropy dips below
random_write_wakeup_bits, we wake up the random writers, so that they
can write some more in. However, the RNDZAPENTCNT/RNDCLEARPOOL ioctl
sets the entropy count to zero -- a potential reduction just like
account() -- but does not unblock writers. This commit adds the missing
logic to that ioctl to unblock waiting writers.

Reviewed-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
parent c321e907

drivers/char/random.c

+4 −1
Original line number Diff line number Diff line
@@ -1856,7 +1856,10 @@ static long random_ioctl(struct file *f, unsigned int cmd, unsigned long arg) 
		 */

		if (!capable(CAP_SYS_ADMIN))

			return -EPERM;

		input_pool.entropy_count = 0;

		if (xchg(&input_pool.entropy_count, 0) && random_write_wakeup_bits) {

			wake_up_interruptible(&random_write_wait);

			kill_fasync(&fasync, SIGIO, POLL_OUT);

		}

		return 0;

	case RNDRESEEDCRNG:

		if (!capable(CAP_SYS_ADMIN))