From: Herbert Xu Subject: Re: Crypto Update for 4.1 Date: Thu, 16 Apr 2015 11:07:13 +0800 Message-ID: <20150416030713.GA11668@gondor.apana.org.au> References: <20140804130339.GA1178@gondor.apana.org.au> <20141007131826.GA29688@gondor.apana.org.au> <20141211125119.GA12380@gondor.apana.org.au> <20150214094328.GA7457@gondor.apana.org.au> <20150415033951.GA1406@gondor.apana.org.au> <20150416024252.GA11558@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Stephan Mueller , "David S. Miller" , Linux Kernel Mailing List , Linux Crypto Mailing List To: Linus Torvalds Return-path: Received: from helcar.hengli.com.au ([209.40.204.226]:56579 "EHLO helcar.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752161AbbDPDH0 (ORCPT ); Wed, 15 Apr 2015 23:07:26 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-crypto-owner@vger.kernel.org List-ID: On Wed, Apr 15, 2015 at 07:49:01PM -0700, Linus Torvalds wrote: > On Wed, Apr 15, 2015 at 7:42 PM, Herbert Xu wrote: > > > > Is CONFIG_CRYPTO_MANAGER_DISABLE_TESTS set or unset in you .config? > > # CONFIG_CRYPTO_MANAGER_DISABLE_TESTS is not set > > I'll send you the full .config in private (no need to spam the mailing > list) in case you have any other questions about my setup. Thanks! It actually appears to be a very simple bug that I somehow missed during reviewing. ---8<--- The commit 9c521a200bc3c12bd724e48a75c57d5358f672be ("crypto: api - remove instance when test failed") tried to grab a module reference count before the module was even set. Worse, it then goes on to free the module reference count after it is set so you quickly end up with a negative module reference count which prevents people from using any instances belonging to that module. This patch moves the module initialisation before the reference count. Reported-by: Linus Torvalds Signed-off-by: Herbert Xu diff --git a/crypto/algapi.c b/crypto/algapi.c index 2d0a1c6..d2627a3 100644 --- a/crypto/algapi.c +++ b/crypto/algapi.c @@ -525,12 +525,12 @@ int crypto_register_instance(struct crypto_template *tmpl, if (err) return err; - if (unlikely(!crypto_mod_get(&inst->alg))) - return -EAGAIN; - inst->alg.cra_module = tmpl->module; inst->alg.cra_flags |= CRYPTO_ALG_INSTANCE; + if (unlikely(!crypto_mod_get(&inst->alg))) + return -EAGAIN; + down_write(&crypto_alg_sem); larval = __crypto_register_alg(&inst->alg); -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt