From: Herbert Xu <herbert@gondor.apana.org.au>
To: Eric Biggers <ebiggers@kernel.org>
Cc: tytso@mit.edu, linux-kernel@vger.kernel.org,
linux-crypto@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH] random: use correct memory barriers for crng_node_pool
Date: Thu, 17 Sep 2020 17:26:44 +1000 [thread overview]
Message-ID: <20200917072644.GA5311@gondor.apana.org.au> (raw)
In-Reply-To: <20200916233042.51634-1-ebiggers@kernel.org>
Eric Biggers <ebiggers@kernel.org> wrote:
> From: Eric Biggers <ebiggers@google.com>
>
> When a CPU selects which CRNG to use, it accesses crng_node_pool without
> a memory barrier. That's wrong, because crng_node_pool can be set by
> another CPU concurrently. Without a memory barrier, the crng_state that
> is used might not appear to be fully initialized.
The only architecture that requires a barrier for data dependency
is Alpha. The correct primitive to ensure that barrier is present
is smp_barrier_depends, or you could just use READ_ONCE.
Cheers,
--
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
next prev parent reply other threads:[~2020-09-17 8:11 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-16 23:30 [PATCH] random: use correct memory barriers for crng_node_pool Eric Biggers
2020-09-17 7:26 ` Herbert Xu [this message]
2020-09-17 16:58 ` Eric Biggers
2020-09-21 8:19 ` Herbert Xu
2020-09-21 15:27 ` Paul E. McKenney
2020-09-21 22:11 ` Herbert Xu
2020-09-21 23:26 ` Paul E. McKenney
2020-09-21 23:51 ` Herbert Xu
2020-09-22 18:42 ` Paul E. McKenney
2020-09-22 18:59 ` Eric Biggers
2020-09-22 20:31 ` Paul E. McKenney
2020-09-21 23:52 ` Eric Biggers
2020-09-22 18:31 ` Paul E. McKenney
2020-09-22 19:09 ` Eric Biggers
2020-09-22 20:56 ` Paul E. McKenney
2020-09-22 21:55 ` Eric Biggers
2020-09-25 0:59 ` Paul E. McKenney
2020-09-25 2:09 ` Eric Biggers
2020-09-25 3:31 ` Paul E. McKenney
2020-10-02 3:07 ` Eric Biggers
2020-10-08 18:31 ` Paul E. McKenney
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