From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45059) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fVJ2B-0001yN-9O for qemu-devel@nongnu.org; Tue, 19 Jun 2018 11:59:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fVJ27-0006FR-D8 for qemu-devel@nongnu.org; Tue, 19 Jun 2018 11:59:07 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:41020 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 1fVJ27-0006Eu-5o for qemu-devel@nongnu.org; Tue, 19 Jun 2018 11:59:03 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 80E917DAC3 for ; Tue, 19 Jun 2018 15:59:02 +0000 (UTC) Date: Tue, 19 Jun 2018 16:58:59 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Message-ID: <20180619155859.GE26829@redhat.com> Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20180619151719.17002-1-berrange@redhat.com> <20180619154504.GI2368@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180619154504.GI2368@work-vm> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] migration: fix crash in when incoming client channel setup fails List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" Cc: qemu-devel@nongnu.org, Juan Quintela On Tue, Jun 19, 2018 at 04:45:05PM +0100, Dr. David Alan Gilbert wrote: > * Daniel P. Berrang=C3=A9 (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. > >=20 > > This means that if channel initialization fails with normal > > migration, it'll never notice and attempt to start the > > incoming migration regardless. >=20 > I'm not sure if that was actually the cause, because older versions > had no check at all in socket_accept_incoming_migration. Hmm, actually your write - it was a complicated series of refactorings for multifd, and I think I mis-identified. I'll do a proper bisect so we can have an accurate record. >=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_migra= tion_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.s= o.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. >=20 > So, what happens with this fix, does the destination exit cleanly, or > stay to accept another connection or what? It stays around and can accept another connection, which is actually quite desirable, as it limits impact of a malicious client from DOS'ing the genuine client by racing to connect first. Regards, Daniel --=20 |: https://berrange.com -o- https://www.flickr.com/photos/dberran= ge :| |: https://libvirt.org -o- https://fstop138.berrange.c= om :| |: https://entangle-photo.org -o- https://www.instagram.com/dberran= ge :|