Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752180AbdHJLfQ (ORCPT ); Thu, 10 Aug 2017 07:35:16 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:43605 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751456AbdHJLfP (ORCPT ); Thu, 10 Aug 2017 07:35:15 -0400 Date: Thu, 10 Aug 2017 14:33:10 +0300 From: Dan Carpenter To: Phil Elwell Cc: Stefan Wahren , devel@driverdev.osuosl.org, Florian Fainelli , Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Eric Anholt , linux-rpi-kernel@lists.infradead.org Subject: Re: [PATCH] staging: bcm2835-audio: Fix memory corruption Message-ID: <20170810113310.vpxyvgpfqq5jikua@mwanda> References: <1502193902-87160-1-git-send-email-phil@raspberrypi.org> <20170810102155.6j373u3yktnlwsqw@mwanda> <20170810112451.nkvj7p6r7qgqqnh3@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170810112451.nkvj7p6r7qgqqnh3@mwanda> User-Agent: NeoMutt/20170113 (1.7.2) X-Source-IP: userv0021.oracle.com [156.151.31.71] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2299 Lines: 50 On Thu, Aug 10, 2017 at 02:24:51PM +0300, Dan Carpenter wrote: > On Thu, Aug 10, 2017 at 11:52:42AM +0100, Phil Elwell wrote: > > On 10/08/2017 11:21, Dan Carpenter wrote: > > > The original patch did not go through the normal review process... > > > > > > On Tue, Aug 08, 2017 at 01:05:02PM +0100, Phil Elwell wrote: > > >> I'm all for fixing memory leaks, but freeing a block while it is still > > >> being used is a recipe for hard-to-debug kernel exceptions. > > >> > > > > > > This bug completely breaks the driver doesn't it? It's not very subtle > > > so it should be easy to diagnose with git bisect. > > > > It's more subtle than that - the failure isn't consistent, sometimes crashing > > and sometimes not depending on how and when memory is reused. > > > > >> 1) There is already a vchi method for freeing the instance, so use it. > > >> 2) Only call it on error, and then only before initted is false. > > >> > > >> Signed-off-by: Phil Elwell > > >> Fixes: 0adbfd4694c2 ("staging: bcm2835-audio: fix memory leak in bcm2835_audio_open_connection()") > > >> --- > > >> drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c | 2 +- > > >> 1 file changed, 1 insertion(+), 1 deletion(-) > > >> > > >> diff --git a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c > > >> index 5f3d8f2..89f96f3 100644 > > >> --- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c > > >> +++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c > > >> @@ -409,6 +409,7 @@ static int bcm2835_audio_open_connection(struct bcm2835_alsa_stream *alsa_stream > > >> LOG_ERR("%s: failed to connect VCHI instance (ret=%d)\n", > > >> __func__, ret); > > >> > > >> + vchi_disconnect(vchi_instance); > > > > > > This is ugly because why are we calling disconnect() if connect() fails? > > > These functions should be symetric so disconnect only disconnects and > > > we call a different function to undo vchi_initialise(). > > > > Agreed - I'm not going to change the API, but I can add a comment. > > > > Nah... Please don't do that. Just create a function: > > static void vchiq_free(VCHIQ_INSTANCE_T *vchi_instance) ^^^^^^ Not static. My bad. regards, dan carpenter