From: Eric Biggers <ebiggers@kernel.org>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: syzbot <syzbot+fc0674cde00b66844470@syzkaller.appspotmail.com>,
davem@davemloft.net, linux-crypto@vger.kernel.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: crypto: api - Fix use-after-free and race in crypto_spawn_alg
Date: Wed, 15 Apr 2020 19:30:01 -0700 [thread overview]
Message-ID: <20200416023001.GE816@sol.localdomain> (raw)
In-Reply-To: <20200416022502.GA18386@gondor.apana.org.au>
On Thu, Apr 16, 2020 at 12:25:02PM +1000, Herbert Xu wrote:
> On Wed, Apr 15, 2020 at 07:17:03PM -0700, Eric Biggers wrote:
> >
> > Wouldn't it be a bit simpler to set 'target = NULL', remove 'shoot',
> > and use 'if (target)' instead of 'if (shoot)'?
>
> Yes it is simpler but it's actually semantically different because
> the compiler doesn't know that spawn->alg cannot be NULL in this
> case.
>
I'm not sure what you mean here. crypto_alg_get() is:
static inline struct crypto_alg *crypto_alg_get(struct crypto_alg *alg)
{
refcount_inc(&alg->cra_refcnt);
return alg;
}
So given:
target = crypto_alg_get(alg);
Both alg and target have to be non-NULL.
- Eric
next prev parent reply other threads:[~2020-04-16 2:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-06 18:16 WARNING: refcount bug in crypto_destroy_tfm syzbot
2020-04-10 6:09 ` crypto: api - Fix use-after-free and race in crypto_spawn_alg Herbert Xu
2020-04-16 2:17 ` Eric Biggers
2020-04-16 2:25 ` Herbert Xu
2020-04-16 2:30 ` Eric Biggers [this message]
2020-04-16 2:42 ` Herbert Xu
2020-04-10 9:18 Markus Elfring
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