hw/cxl: Check input length is large enough in cmd_events_clear_records()

Buggy software might write a message that is too short for
either the header, or the header + the event data that is specified
in the header.  This may result in accesses beyond the range of the
message allocated as a duplicate of the incoming message buffer.

Reported-by: Esifiel <esifiel@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Message-Id: <20241101133917.27634-4-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index e63140aefe70e3e9071e12c390599a553fcd9095..3cb499a24fd35dd0923576777eca2eb96f6f0c78 100644 (file)
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -266,6 +266,12 @@ static CXLRetCode cmd_events_clear_records(const struct cxl_cmd *cmd,
     CXLClearEventPayload *pl;
 
     pl = (CXLClearEventPayload *)payload_in;
+
+    if (len_in < sizeof(*pl) ||
+        len_in < sizeof(*pl) + sizeof(*pl->handle) * pl->nr_recs) {
+        return CXL_MBOX_INVALID_PAYLOAD_LENGTH;
+    }
+
     *len_out = 0;
     return cxl_event_clear_records(cxlds, pl);
 }