[PATCH qemu] hw/cxl: Check for zero length features in cmd_features_set_feature()

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

Zero length data for features doesn't make any sense so exclude that case
early. This fixes the undefined behavior reported by coverity for a zero
length memcpy().

Resolves CID 1564900 and 1564901

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
 hw/cxl/cxl-mailbox-utils.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 2d4d62c454..ce9aa18364 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -1288,6 +1288,10 @@ static CXLRetCode cmd_features_set_feature(const struct cxl_cmd *cmd,
     set_feat_info->data_offset = hdr->offset;
     bytes_to_copy = len_in - sizeof(CXLSetFeatureInHeader);
 
+    if (bytes_to_copy == 0) {
+        return CXL_MBOX_INVALID_PAYLOAD_LENGTH;
+    }
+
     if (qemu_uuid_is_equal(&hdr->uuid, &patrol_scrub_uuid)) {
         if (hdr->version != CXL_MEMDEV_PS_SET_FEATURE_VERSION) {
             return CXL_MBOX_UNSUPPORTED;
-- 
2.43.0