From: Jonathan Cameron <Jonathan.Cameron@huawei.com>

A buggy guest might write an insufficiently large message.
Check the header is present. Whilst zero data after the header is very
odd it will just result in failure to copy any data.

Reported-by: Esifiel <esifiel@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20241101133917.27634-3-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/cxl/cxl-mailbox-utils.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 17924410dd..e63140aefe 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -1238,6 +1238,9 @@ static CXLRetCode cmd_features_set_feature(const struct cxl_cmd *cmd,
     CXLType3Dev *ct3d;
     uint16_t count;
 
+    if (len_in < sizeof(*hdr)) {
+        return CXL_MBOX_INVALID_PAYLOAD_LENGTH;
+    }
 
     if (!object_dynamic_cast(OBJECT(cci->d), TYPE_CXL_TYPE3)) {
         return CXL_MBOX_UNSUPPORTED;
-- 
MST