From: Jiahui Cen
One multifd channel will shutdown all the other multifd's IOChannel when it
fails to receive an IOChannel. In this senario, if some multifds had not
received its IOChannel yet, it would try to shutdown its IOChannel which could
cause nullptr access at qio_channel_shutdown.
Here is the coredump stack:
#0 object_get_class (obj=obj@entry=0x0) at qom/object.c:908
#1 0x5563fdbb8f4a in qio_channel_shutdown (ioc=0x0,
how=QIO_CHANNEL_SHUTDOWN_BOTH, errp=0x0) at io/channel.c:355
#2 0x5563fd7b4c5f in multifd_recv_terminate_threads (err=) at migration/ram.c:1280
#3 0x5563fd7bc019 in multifd_recv_new_channel
(ioc=ioc@entry=0x556400255610, errp=errp@entry=0x7ffec07dce00) at
migration/ram.c:1478
#4 0x5563fda82177 in migration_ioc_process_incoming
(ioc=ioc@entry=0x556400255610, errp=errp@entry=0x7ffec07dce30) at
migration/migration.c:605
#5 0x5563fda8567d in migration_channel_process_incoming
(ioc=0x556400255610) at migration/channel.c:44
#6 0x5563fda83ee0 in socket_accept_incoming_migration
(listener=0x5563fff6b920, cioc=0x556400255610, opaque=) at
migration/socket.c:166
#7 0x5563fdbc25cd in qio_net_listener_channel_func (ioc=, condition=, opaque=) at io/net-listener.c:54
#8 0x7f895b6fe9a9 in g_main_context_dispatch () from
/usr/lib64/libglib-2.0.so.0
#9 0x5563fdc18136 in glib_pollfds_poll () at util/main-loop.c:218
#10 0x5563fdc181b5 in os_host_main_loop_wait (timeout=10) at
util/main-loop.c:241
#11 0x5563fdc183a2 in main_loop_wait (nonblocking=nonblocking@entry=0)
at util/main-loop.c:517
#12 0x5563fd8edb37 in main_loop () at vl.c:1791
#13 0x5563fd74fd45 in main (argc=, argv=,
envp=) at vl.c:4473
To fix it up, let's check p->c before calling qio_channel_shutdown.
Signed-off-by: Jiahui Cen
Signed-off-by: Ying Fang
---
migration/ram.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/migration/ram.c b/migration/ram.c
index 5078f94..dc63692 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1280,7 +1280,9 @@ static void multifd_recv_terminate_threads(Error *err)
- normal quit, i.e. everything went fine, just finished
- error quit: We close the channels so the channel threads
finish the qio_channel_read_all_eof() */
-qio_channel_shutdown(p->c, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+if (p->c) {
+qio_channel_shutdown(p->c, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
+}
qemu_mutex_unlock(>mutex);
}
}
--
1.8.3.1
