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Commit 9924c212 authored by Dominik Brodowski's avatar Dominik Brodowski Committed by Greg Kroah-Hartman
Browse files

random: fix locking in crng_fast_load() 



commit 7c2fe2b32bf76441ff5b7a425b384e5f75aa530a upstream.

crng_init is protected by primary_crng->lock, so keep holding that lock
when incrementing crng_init from 0 to 1 in crng_fast_load(). The call to
pr_notice() can wait until the lock is released; this code path cannot
be reached twice, as crng_fast_load() aborts early if crng_init > 0.

Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 90ebbb47

drivers/char/random.c

+3 −2
Original line number Diff line number Diff line
@@ -647,12 +647,13 @@ static size_t crng_fast_load(const u8 *cp, size_t len) 
		p[crng_init_cnt % CHACHA20_KEY_SIZE] ^= *cp;

		cp++; crng_init_cnt++; len--; ret++;

	}

	spin_unlock_irqrestore(&primary_crng.lock, flags);

	if (crng_init_cnt >= CRNG_INIT_CNT_THRESH) {

		invalidate_batched_entropy();

		crng_init = 1;

		pr_notice("fast init done\n");

	}

	spin_unlock_irqrestore(&primary_crng.lock, flags);

	if (crng_init == 1)

		pr_notice("fast init done\n");

	return ret;

}