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random: fix locking in crng_fast_load()

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commit 7c2fe2b32b 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 <linux@dominikbrodowski.net>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dominik Brodowski 2022-02-05 11:34:57 +01:00 committed by Greg Kroah-Hartman
parent 048d57faf9
commit ba20054937
1 changed files with 3 additions and 2 deletions
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5
drivers/char/random.c
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@ -647,12 +647,13 @@ 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;
}