linux-kernel - Re: crypto: use-after-free in alg

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Message-ID: <20151230105300.GA10383@gondor.apana.org.au>
Date:	Wed, 30 Dec 2015 18:53:00 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Dmitry Vyukov <dvyukov@...gle.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	linux-crypto@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Kostya Serebryany <kcc@...gle.com>,
	Alexander Potapenko <glider@...gle.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Eric Dumazet <edumazet@...gle.com>,
	syzkaller <syzkaller@...glegroups.com>
Subject: Re: crypto: use-after-free in alg_bind

On Wed, Dec 30, 2015 at 11:19:45AM +0100, Dmitry Vyukov wrote:
>
> This use-after-free does not reproduce on every run. It seems to be
> triggered by some race. Try to run the program in a parallel loop.
> I use stress tool for this:
> https://github.com/golang/tools/blob/master/cmd/stress/stress.go
> If you have Go toolchain installed, then then following will do:
> $ go get golang.org/x/tools/cmd/stress
> $ stress -p 16 ./a.out

I've tried a few thousand instances of it but still no luck.
> 
> 
> diff --git a/crypto/af_alg.c b/crypto/af_alg.c
> index a8e7aa3..82a7dcd 100644

There are a few missing hunks in your patch and the patch to
if_alg.h is missing.

So please start with the current crypto tree and then apply the
latest version (v2) of "crypto: af_alg - Disallow bind/setkey/...
after accept(2)" and try again.

Thanks,
-- 
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
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