From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753300AbbJZHo3 (ORCPT ); Mon, 26 Oct 2015 03:44:29 -0400 Received: from metis.ext.4.pengutronix.de ([92.198.50.35]:60277 "EHLO metis.ext.pengutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752984AbbJZHoZ (ORCPT ); Mon, 26 Oct 2015 03:44:25 -0400 Date: Mon, 26 Oct 2015 08:44:17 +0100 From: Markus Pargmann To: Oleg Nesterov Cc: Andrew Morton , nbd-general@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH -mm 2/3] nbd: nbd_thread_recv: remove the buggy kernel_dequeue_signal() Message-ID: <20151026074417.GE16521@pengutronix.de> References: <20151025152625.GA1385@redhat.com> <20151025152639.GA1402@redhat.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="qOrJKOH36bD5yhNe" Content-Disposition: inline In-Reply-To: <20151025152639.GA1402@redhat.com> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 08:35:44 up 36 days, 20:57, 161 users, load average: 0.25, 0.39, 1.10 User-Agent: Mutt/1.5.24 (2015-08-30) X-SA-Exim-Connect-IP: 2001:67c:670:100:1d::7 X-SA-Exim-Mail-From: mpa@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-kernel@vger.kernel.org Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --qOrJKOH36bD5yhNe Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Oleg, On Sun, Oct 25, 2015 at 04:26:39PM +0100, Oleg Nesterov wrote: > nbd_thread_recv() is called by userspace, it is very wrong to dequeue > and throw out a signal. This signal handling for a userspace process is implicitly implemented for several years already through the timeout handling. This is nothing new and could potentially break userspace if someone disconnects NBD using the kill command. As we expose the appropriate PID of the process as well this is possible to be used in an init script. So I am not sure about this patch yet. >=20 > I do not understand why nbd_thread_recv() (and nbd_thread_send() btw) > does sock_shutdown(); the caller, __nbd_ioctl(NBD_DO_IT) does this too. Yes indeed. This has to be fixed as well, thanks. Best Regards, Markus >=20 > Signed-off-by: Oleg Nesterov > --- > drivers/block/nbd.c | 5 ++--- > 1 files changed, 2 insertions(+), 3 deletions(-) >=20 > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c > index e5d96e5..0ffd73c 100644 > --- a/drivers/block/nbd.c > +++ b/drivers/block/nbd.c > @@ -444,9 +444,8 @@ static int nbd_thread_recv(struct nbd_device *nbd) > spin_unlock_irqrestore(&nbd->tasks_lock, flags); > =20 > if (signal_pending(current)) { > - ret =3D kernel_dequeue_signal(NULL); > - dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n", > - task_pid_nr(current), current->comm, ret); > + dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal", > + task_pid_nr(current), current->comm); > mutex_lock(&nbd->tx_lock); > sock_shutdown(nbd); > mutex_unlock(&nbd->tx_lock); > --=20 > 1.5.5.1 >=20 >=20 --=20 Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | --qOrJKOH36bD5yhNe Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQIcBAEBAgAGBQJWLdnRAAoJEEpcgKtcEGQQ1aIP/ivg3AYSuXyeq10pQCmAswmj RWWW7ifcwPFrvUBmpO9eV4yJzhul5E/n0vJaeszO3WBLKlQYGCdfhMbHBMwGlO45 70uQOIy58OOHkmO9Sgk0rSVT4zsZZaJqu7LPD4ckw+blmTSFL1q+xl/rGW80HIzy FYk5hJTZ/5pmEcaIhV3627znzPJuJpX7+UEdtR9NRey7nJkPqqhBv6pOYCaU8AiN 5yubO3fhFe+fDFswNvxWcQ7+9cVyEastHTwf63U4lDa7eTXaIXqkJArQNuOBucAf lW5LDe717RXJoTMqbH3DJ3I6M72HjJ5gQEojpu7+eL12yA/9iBBll8wUvV8qD6yp z7/TqlxNxKK6eMZ2Cpnk3yOfHlrxWLtfXnlBhsnEJ2pnxzrsLYRR2DcGBL1nUxww dzKeMnAcGuDcLQm1PCS1DkBRy84+LOIJV01T2A3hyVvzGmPYE11Gi/EZY3ZCw0L2 PXK7sgGiXwXBLq0Svx4VUzd5MDRgG051/qtNtVcVyleVWrV/x8Z0zKzNa2eukqFm jeQUy3v9qKpH+tZD4Zmu42TMD/AK7qeaOy6IcWEVrGmw5gAowJ6Bi6+DwfjjHjlH 6zFzwgZ+S62Kr5k5+NRn++tsSHwytD4IpOs+dSPZaSFeF8z22MO+hIvDbaxM3jJq uMYw7YqG0nKKnKOkKvO0 =c4rN -----END PGP SIGNATURE----- --qOrJKOH36bD5yhNe--