[Qemu-devel] [PATCH 1/1] migration: fix use-after-free in loadvm_postcopy_handle_run_bh

[Denis V. Lunev]

MigrationState is destroyed before we can come into bottom half.

Signed-off-by: Denis V. Lunev <address@hidden>
CC: Juan Quintela <address@hidden>
CC: Amit Shah <address@hidden>
CC: Dr. David Alan Gilbert <address@hidden>
---
Dave, do you have tests you have mention available on public? I'd better
run them in advance next time.

 migration/savevm.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index 96e7db5..384e872 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1501,10 +1501,15 @@ static int 
loadvm_postcopy_handle_listen(MigrationIncomingState *mis)
     return 0;
 }
 
+
+typedef struct {
+    QEMUBH *bh;
+} HandleRunBhData;
+
 static void loadvm_postcopy_handle_run_bh(void *opaque)
 {
     Error *local_err = NULL;
-    MigrationIncomingState *mis = opaque;
+    HandleRunBhData *data = opaque;
 
     /* TODO we should move all of this lot into postcopy_ram.c or a shared code
      * in migration.c
@@ -1532,13 +1537,15 @@ static void loadvm_postcopy_handle_run_bh(void *opaque)
         runstate_set(RUN_STATE_PAUSED);
     }
 
-    qemu_bh_delete(mis->bh);
+    qemu_bh_delete(data->bh);
+    g_free(data);
 }
 
 /* After all discards we can start running and asking for pages */
 static int loadvm_postcopy_handle_run(MigrationIncomingState *mis)
 {
     PostcopyState ps = postcopy_state_set(POSTCOPY_INCOMING_RUNNING);
+    HandleRunBhData *data;
 
     trace_loadvm_postcopy_handle_run();
     if (ps != POSTCOPY_INCOMING_LISTENING) {
@@ -1546,8 +1553,9 @@ static int 
loadvm_postcopy_handle_run(MigrationIncomingState *mis)
         return -1;
     }
 
-    mis->bh = qemu_bh_new(loadvm_postcopy_handle_run_bh, NULL);
-    qemu_bh_schedule(mis->bh);
+    data = g_new(HandleRunBhData, 1);
+    data->bh = qemu_bh_new(loadvm_postcopy_handle_run_bh, data);
+    qemu_bh_schedule(data->bh);
 
     /* We need to finish reading the stream from the package
      * and also stop reading anything more from the stream that loaded the
-- 
2.1.4