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 <jialin...@baidu.com> Signed-off-by: Chai Wen <chai...@baidu.com> Signed-off-by: Zhang Yu <zhangy...@baidu.com> --- migration/migration.c | 2 +- migration/migration.h | 2 ++ migration/savevm.c | 19 +++++++++++-------- 3 files changed, 14 insertions(+), 9 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index d6ae879dc8..b5e71c7bfc 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -711,7 +711,7 @@ MigrationParameters *qmp_query_migrate_parameters(Error **errp) * Return true if we're already in the middle of a migration * (i.e. any of the active or setup states) */ -static bool migration_is_setup_or_active(int state) +bool migration_is_setup_or_active(int state) { switch (state) { case MIGRATION_STATUS_ACTIVE: diff --git a/migration/migration.h b/migration/migration.h index f7813f8261..e413d4d8b6 100644 --- a/migration/migration.h +++ b/migration/migration.h @@ -241,6 +241,8 @@ void migrate_fd_error(MigrationState *s, const Error *error); void migrate_fd_connect(MigrationState *s, Error *error_in); +bool migration_is_setup_or_active(int state); + void migrate_init(MigrationState *s); bool migration_is_blocked(Error **errp); /* True if outgoing migration has entered postcopy phase */ diff --git a/migration/savevm.c b/migration/savevm.c index 2d10e45582..eeade8cb92 100644 --- a/migration/savevm.c +++ b/migration/savevm.c @@ -1319,21 +1319,25 @@ 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); @@ -1355,7 +1359,6 @@ 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 { -- 2.13.2.windows.1