[PULL,11/15] migration/rdma: Fix cm_event used before being initialized

Commit Message

Dr. David Alan Gilbert May 26, 2021, 5:45 p.m. UTC

From: Li Zhijian <[e-mail]>

A segmentation fault was triggered when i try to abort a postcopy + rdma
migration.

since rdma_ack_cm_event releases a uninitialized cm_event in these case.

like below:
2496     ret = rdma_get_cm_event(rdma->channel, &cm_event);
2497     if (ret) {
2498         perror("rdma_get_cm_event after rdma_connect");
2499         ERROR(errp, "connecting to destination!");
2500         rdma_ack_cm_event(cm_event); <<<< cause segmentation fault
2501         goto err_rdma_source_connect;
2502     }

Refer to the rdma_get_cm_event() code, cm_event will be
updated/changed only if rdma_get_cm_event() returns 0. So it's okey to
remove the ack in error patch.

Signed-off-by: Li Zhijian <[e-mail]>

Message-Id: <[e-mail]>
Reviewed-by: Dr. David Alan Gilbert <[e-mail]>
Signed-off-by: Dr. David Alan Gilbert <[e-mail]>
---
 migration/rdma.c | 1 -
 1 file changed, 1 deletion(-)

Patch

diff --git a/migration/rdma.c b/migration/rdma.c
index 00eac34232..41726cc74a 100644
--- a/migration/rdma.c
+++ b/migration/rdma.c
@@ -2497,7 +2497,6 @@  static int qemu_rdma_connect(RDMAContext *rdma, Error **errp)
     if (ret) {
         perror("rdma_get_cm_event after rdma_connect");
         ERROR(errp, "connecting to destination!");
-        rdma_ack_cm_event(cm_event);
         goto err_rdma_source_connect;
     }