From: Dominik Brodowski Date: Sat, 5 Feb 2022 10:34:57 +0000 (+0100) Subject: random: fix locking in crng_fast_load() X-Git-Tag: v4.19.249~153 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=077c1e48a8c9943fedec1c447f83f7ab39c5da1d;p=thirdparty%2Fkernel%2Fstable.git 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: Dominik Brodowski Reviewed-by: Eric Biggers Signed-off-by: Jason A. Donenfeld Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/char/random.c b/drivers/char/random.c index 5d6a9a9be4625..5cc10ec3d44fb 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -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; }