From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756208Ab1AaRj7 (ORCPT ); Mon, 31 Jan 2011 12:39:59 -0500 Received: from mx01.sz.bfs.de ([194.94.69.103]:50855 "EHLO mx01.sz.bfs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751543Ab1AaRj5 (ORCPT ); Mon, 31 Jan 2011 12:39:57 -0500 Message-ID: <4D46F3E5.7060804@bfs.de> Date: Mon, 31 Jan 2011 18:39:49 +0100 From: walter harms Reply-To: wharms@bfs.de User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; de; rv:1.9.1.16) Gecko/20101125 SUSE/3.0.11 Thunderbird/3.0.11 MIME-Version: 1.0 To: Julia Lawall CC: Lars Ellenberg , kernel-janitors@vger.kernel.org, drbd-user@lists.linbit.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] drivers/block/drbd: add NULL test around call to crypto_free_hash References: <1296496263-16362-1-git-send-email-julia@diku.dk> In-Reply-To: <1296496263-16362-1-git-send-email-julia@diku.dk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 31.01.2011 18:51, schrieb Julia Lawall: > crypto_free_hash calls the function crypto_hash_tfm and then > crypto_free_tfm on the result. crypto_free_tfm calls crypto_destroy_tfm, > which tests this result for NULL and then dereferences it. crypto_hash_tfm > returns &tfm->base where tfm is its argument. base is actually the first > and only field of a crypto_hash-typed structure, so perhaps one can rely on > it to return NULL for a NULL value of tfm. But most calls to > crypto_hash_tfm where the argument might be NULL don't rely on this > property and test for NULL explicitly. > > The semantic match that finds this problem is as follows: > (http://coccinelle.lip6.fr/) > > // > @safe@ > position p; > expression x; > @@ > > if (x) { <+... crypto_free_hash@p(x) ...+> } > > @@ > expression x; > position p!=safe.p; > @@ > > *x = NULL > ... > *crypto_free_hash@p(x) > // > > Signed-off-by: Julia Lawall > > --- > drivers/block/drbd/drbd_nl.c | 18 ++++++++++++------ > drivers/block/drbd/drbd_receiver.c | 6 ++++-- > 2 files changed, 16 insertions(+), 8 deletions(-) > > diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c > index 8cbfaa6..aa5fbc0 100644 > --- a/drivers/block/drbd/drbd_nl.c > +++ b/drivers/block/drbd/drbd_nl.c > @@ -1482,13 +1482,16 @@ static int drbd_nl_net_conf(struct drbd_conf *mdev, struct drbd_nl_cfg_req *nlp, > mdev->ee_hash = new_ee_hash; > } > > - crypto_free_hash(mdev->cram_hmac_tfm); > + if (mdev->cram_hmac_tfm) > + crypto_free_hash(mdev->cram_hmac_tfm); > mdev->cram_hmac_tfm = tfm; > > - crypto_free_hash(mdev->integrity_w_tfm); > + if (mdev->integrity_w_tfm) > + crypto_free_hash(mdev->integrity_w_tfm); > mdev->integrity_w_tfm = integrity_w_tfm; > > - crypto_free_hash(mdev->integrity_r_tfm); > + if (mdev->integrity_r_tfm) > + crypto_free_hash(mdev->integrity_r_tfm); > mdev->integrity_r_tfm = integrity_r_tfm; > > kfree(mdev->int_dig_out); > @@ -1509,9 +1512,12 @@ fail: > kfree(int_dig_out); > kfree(int_dig_in); > kfree(int_dig_vv); > - crypto_free_hash(tfm); > - crypto_free_hash(integrity_w_tfm); > - crypto_free_hash(integrity_r_tfm); > + if (tfm) > + crypto_free_hash(tfm); > + if (integrity_w_tfm) > + crypto_free_hash(integrity_w_tfm); > + if (integrity_r_tfm) > + crypto_free_hash(integrity_r_tfm); > kfree(new_tl_hash); > kfree(new_ee_hash); > kfree(new_conf); > diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c > index 24487d4..3453cc3 100644 > --- a/drivers/block/drbd/drbd_receiver.c > +++ b/drivers/block/drbd/drbd_receiver.c > @@ -2871,9 +2871,11 @@ static int receive_SyncParam(struct drbd_conf *mdev, enum drbd_packets cmd, unsi > disconnect: > /* just for completeness: actually not needed, > * as this is not reached if csums_tfm was ok. */ > - crypto_free_hash(csums_tfm); > + if (csums_tfm) > + crypto_free_hash(csums_tfm); > /* but free the verify_tfm again, if csums_tfm did not work out */ > - crypto_free_hash(verify_tfm); > + if (verify_tfm) > + crypto_free_hash(verify_tfm); > drbd_force_state(mdev, NS(conn, C_DISCONNECTING)); > return FALSE; > } > it looks that it would be more sensibel to change crypto_free_hash() to handle NULL that would be more consistent with the free() family. just my 2 cents, re, wh