The OCPP 1.6 client in subsys\/net\/lib\/ocpp parsed inbound WAMP RPC frames in parse_rpc_msg() (subsys\/net\/lib\/ocpp\/ocpp_j.c) using a hand-rolled helper, extract_string_field(), that copied the message’s uid and action fields with strncpy(out_buf, token + 1, outlen – 1) and then scanned the result with strchr(out_buf, ‘”‘). Because strncpy does not NUL-terminate the destination when the source is at least outlen – 1 (127) bytes long, the subsequent strchr reads past the 128-byte destination buffer into adjacent stack memory; if a ” byte is found beyond the buffer, a one-byte out-of-bounds NUL write also occurs. A related defect in extract_payload() runs strchr\/strrchr over the receive buffer, which may not be NUL-terminated when a maximal-length frame fills it.<\/p>\n
The parsed bytes come directly from the OCPP central-system server over a websocket: the reader thread fills recv_buf via websocket_recv_msg() and calls parse_rpc_msg() on each inbound DATA frame (subsys\/net\/lib\/ocpp\/ocpp.c). A malicious or compromised central server, or an on-path attacker (OCPP is commonly deployed over plain ws:\/\/), can send an RPC frame whose uid or action field is 127+ bytes with no closing quote, triggering the out-of-bounds access.<\/p>\n
The primary impact is a remotely triggerable denial of service: the unbounded scan can fault on an unmapped page, and the stray NUL write can corrupt adjacent stack state. The over-read data is not reflected to the peer, so disclosure is limited. The feature is EXPERIMENTAL and must be explicitly enabled (CONFIG_OCPP). The fix replaces the manual parser with the bounds-respecting json_mixed_arr_parse() and copies the extracted uid with an explicitly NUL-terminated buffer, eliminating both over-reads.<\/p>\n","protected":false},"excerpt":{"rendered":"
The OCPP 1.6 client in subsys\/net\/lib\/ocpp parsed inbound WAMP RPC frames in parse_rpc_msg() (subsys\/net\/lib\/ocpp\/ocpp_j.c) using a hand-rolled helper, extract_string_field(), that copied the message’<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-4320","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/4320","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=4320"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=4320"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=4320"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}