[PATCH v3] hw/pvrdma: Protect against buggy or malicious guest driver

[Yuval Shaia]

Guest driver might execute HW commands when shared buffers are not yet
allocated.
This could happen on purpose (malicious guest) or because of some other
guest/host address mapping error.
We need to protect againts such case.

Fixes: CVE-2022-1050

Reported-by: Raven <wxhusst@gmail.com>
Signed-off-by: Yuval Shaia <yuval.shaia.ml@gmail.com>
---
v1 -> v2:
        * Commit message changes
v2 -> v3:
        * Exclude cosmetic changes
---
 hw/rdma/vmw/pvrdma_cmd.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/rdma/vmw/pvrdma_cmd.c b/hw/rdma/vmw/pvrdma_cmd.c
index da7ddfa548..89db963c46 100644
--- a/hw/rdma/vmw/pvrdma_cmd.c
+++ b/hw/rdma/vmw/pvrdma_cmd.c
@@ -796,6 +796,12 @@ int pvrdma_exec_cmd(PVRDMADev *dev)
 
     dsr_info = &dev->dsr_info;
 
+    if (!dsr_info->dsr) {
+            /* Buggy or malicious guest driver */
+            rdma_error_report("Exec command without dsr, req or rsp buffers");
+            goto out;
+    }
+
     if (dsr_info->req->hdr.cmd >= sizeof(cmd_handlers) /
                       sizeof(struct cmd_handler)) {
         rdma_error_report("Unsupported command");
-- 
2.20.1