linux-kernel - Re: crypto: api - Fix use-after-free and race in crypto_spawn

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Message-ID: <20200416024216.GA18571@gondor.apana.org.au>
Date:   Thu, 16 Apr 2020 12:42:16 +1000
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     syzbot <syzbot+fc0674cde00b66844470@...kaller.appspotmail.com>,
        davem@...emloft.net, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: crypto: api - Fix use-after-free and race in crypto_spawn_alg

On Wed, Apr 15, 2020 at 07:30:01PM -0700, Eric Biggers wrote:
> 
> 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.

Yes I know that we know that it can't be NULL, but gcc 8.3 doesn't.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt