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random: fix locking for crng_init in crng_reseed()

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crng_init is protected by primary_crng->lock. Therefore, we need
to hold this lock when increasing crng_init to 2. As we shouldn't
hold this lock for too long, only hold it for those parts which
require protection.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Dominik Brodowski 2022-02-09 19:57:06 +01:00 committed by Jason A. Donenfeld
parent 7b5164fb12
commit 7191c628fe
1 changed files with 6 additions and 3 deletions
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9
drivers/char/random.c
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@ -502,6 +502,7 @@ static void crng_reseed(void)
int entropy_count;
unsigned long next_gen;
u8 key[CHACHA_KEY_SIZE];
bool finalize_init = false;
/*
* First we make sure we have POOL_MIN_BITS of entropy in the pool,
@ -529,12 +530,14 @@ static void crng_reseed(void)
++next_gen;
WRITE_ONCE(base_crng.generation, next_gen);
WRITE_ONCE(base_crng.birth, jiffies);
spin_unlock_irqrestore(&base_crng.lock, flags);
memzero_explicit(key, sizeof(key));
if (crng_init < 2) {
invalidate_batched_entropy();
crng_init = 2;
finalize_init = true;
}
spin_unlock_irqrestore(&base_crng.lock, flags);
memzero_explicit(key, sizeof(key));
if (finalize_init) {
process_random_ready_list();
wake_up_interruptible(&crng_init_wait);
kill_fasync(&fasync, SIGIO, POLL_IN);