| Message ID | 20220205103458.133386-2-linux@dominikbrodowski.net |
|---|---|
| State | Accepted |
| Commit | 7c2fe2b32bf76441ff5b7a425b384e5f75aa530a |
| Headers | show |
| Series | random: fix write locking for crng_init | expand |
On Sat, Feb 05, 2022 at 11:34:57AM +0100, Dominik Brodowski wrote: > 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 <linux@dominikbrodowski.net> > --- > drivers/char/random.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) Reviewed-by: Eric Biggers <ebiggers@google.com> - Eric
diff --git a/drivers/char/random.c b/drivers/char/random.c index 5d7d6e01bbc4..2df08d05e850 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -653,12 +653,13 @@ static size_t crng_fast_load(const u8 *cp, size_t len) p[crng_init_cnt % CHACHA_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; }
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 <linux@dominikbrodowski.net> --- drivers/char/random.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)