From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:57479) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fVJgO-0001k6-EK for qemu-devel@nongnu.org; Tue, 19 Jun 2018 12:40:42 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fVJgK-00009T-FS for qemu-devel@nongnu.org; Tue, 19 Jun 2018 12:40:40 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:47776 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fVJgK-000091-2C for qemu-devel@nongnu.org; Tue, 19 Jun 2018 12:40:36 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 77EE28780F for ; Tue, 19 Jun 2018 16:40:35 +0000 (UTC) Date: Tue, 19 Jun 2018 17:40:32 +0100 From: "Dr. David Alan Gilbert" Message-ID: <20180619164032.GL2368@work-vm> References: <20180619163552.18206-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20180619163552.18206-1-berrange@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH v2] migration: fix crash in when incoming client channel setup fails List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Daniel =?iso-8859-1?Q?P=2E_Berrang=E9?= Cc: qemu-devel@nongnu.org, Juan Quintela * Daniel P. Berrang=E9 (berrange@redhat.com) wrote: > The way we determine if we can start the incoming migration was > changed to use migration_has_all_channels() in: >=20 > commit 428d89084c709e568f9cd301c2f6416a54c53d6d > Author: Juan Quintela > Date: Mon Jul 24 13:06:25 2017 +0200 >=20 > migration: Create migration_has_all_channels >=20 > This method in turn calls multifd_recv_all_channels_created() > which is hardcoded to always return 'true' when multifd is > not in use. This is a latent bug... >=20 > ...activated in in a following commit where that return result > ends up acting as the flag to indicate whether it is possible > to start processing the migration: >=20 > commit 36c2f8be2c4eb0003ac77a14910842b7ddd7337e > Author: Juan Quintela > Date: Wed Mar 7 08:40:52 2018 +0100 >=20 > migration: Delay start of migration main routines >=20 > This means that if channel initialization fails with normal > migration, it'll never notice and attempt to start the > incoming migration regardless and crash on a NULL pointer. >=20 > This can be seen, for example, if a client connects to a server > requiring TLS, but has an invalid x509 certificate: >=20 > qemu-system-x86_64: The certificate hasn't got a known issuer > qemu-system-x86_64: migration/migration.c:386: process_incoming_migrati= on_co: Assertion `mis->from_src_file' failed. >=20 > #0 0x00007fffebd24f2b in raise () at /lib64/libc.so.6 > #1 0x00007fffebd0f561 in abort () at /lib64/libc.so.6 > #2 0x00007fffebd0f431 in _nl_load_domain.cold.0 () at /lib64/libc.so.= 6 > #3 0x00007fffebd1d692 in () at /lib64/libc.so.6 > #4 0x0000555555ad027e in process_incoming_migration_co (opaque=3D) at migration/migration.c:386 > #5 0x0000555555c45e8b in coroutine_trampoline (i0=3D, = i1=3D) at util/coroutine-ucontext.c:116 > #6 0x00007fffebd3a6a0 in __start_context () at /lib64/libc.so.6 > #7 0x0000000000000000 in () >=20 > To handle the non-multifd case, we check whether mis->from_src_file > is non-NULL. With this in place, the migration server drops the > rejected client and stays around waiting for another, hopefully > valid, client to arrive. >=20 > Signed-off-by: Daniel P. Berrang=E9 Reviewed-by: Dr. David Alan Gilbert > --- >=20 > Changed in v2: >=20 > - Clarify exactly when it broke > - Clarify that we expect the server to stay active >=20 > migration/migration.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) >=20 > diff --git a/migration/migration.c b/migration/migration.c > index e1eaa97df4..38ad818b23 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -518,11 +518,12 @@ void migration_ioc_process_incoming(QIOChannel *i= oc) > */ > bool migration_has_all_channels(void) > { > + MigrationIncomingState *mis =3D migration_incoming_get_current(); > bool all_channels; > =20 > all_channels =3D multifd_recv_all_channels_created(); > =20 > - return all_channels; > + return all_channels && mis->from_src_file !=3D NULL; > } > =20 > /* > --=20 > 2.17.0 >=20 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK