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[Qemu-devel] [PULL 3/3] migration: avoid segmentfault when take a snapsh
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [PULL 3/3] migration: avoid segmentfault when take a snapshot of a VM which being migrated |
Date: |
Wed, 31 Oct 2018 16:57:25 +0000 |
From: Jia Lina <address@hidden>
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 <address@hidden>
Signed-off-by: Chai Wen <address@hidden>
Signed-off-by: Zhang Yu <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: Dr. David Alan Gilbert <address@hidden>
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
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 8b36e7f184..b261c1e4ce 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -742,7 +742,7 @@ 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 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 {
--
2.19.1