From 3d63da16fbcd05405efd5946000cdb45474a9bad Mon Sep 17 00:00:00 2001 From: Jia Lina Date: Fri, 26 Oct 2018 16:36:20 +0800 Subject: migration: avoid segmentfault when take a snapshot of a VM which being migrated During an active background migration, snapshot will trigger a segmentfault. As snapshot clears the "current_migration" struct and updates "to_dst_file" before it finds out that there is a migration task, Migration accesses the null pointer in "current_migration" struct and qemu crashes eventually. Signed-off-by: Jia Lina Signed-off-by: Chai Wen Signed-off-by: Zhang Yu Message-Id: <20181026083620.10172-1-jialina01@baidu.com> Reviewed-by: Dr. David Alan Gilbert Signed-off-by: Dr. David Alan Gilbert --- migration/savevm.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) (limited to 'migration/savevm.c') diff --git a/migration/savevm.c b/migration/savevm.c index 9992af4db4..ef707b8c43 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1327,21 +1327,25 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp) MigrationState *ms = migrate_get_current(); MigrationStatus status; - migrate_init(ms); - - ms->to_dst_file = f; + if (migration_is_setup_or_active(ms->state) || + ms->state == MIGRATION_STATUS_CANCELLING || + ms->state == MIGRATION_STATUS_COLO) { + error_setg(errp, QERR_MIGRATION_ACTIVE); + return -EINVAL; + } if (migration_is_blocked(errp)) { - ret = -EINVAL; - goto done; + return -EINVAL; } if (migrate_use_block()) { error_setg(errp, "Block migration and snapshots are incompatible"); - ret = -EINVAL; - goto done; + return -EINVAL; } + migrate_init(ms); + ms->to_dst_file = f; + qemu_mutex_unlock_iothread(); qemu_savevm_state_header(f); qemu_savevm_state_setup(f); @@ -1363,7 +1367,6 @@ static int qemu_savevm_state(QEMUFile *f, Error **errp) error_setg_errno(errp, -ret, "Error while writing VM state"); } -done: if (ret != 0) { status = MIGRATION_STATUS_FAILED; } else { -- cgit v1.2.3-55-g7522