[PATCH] net: qrtr: ns: validate msglen and sq_port in qrtr_ns_worker() and ctrl_cmd_bye()

[Hui Peng]

Two validation checks are missing in the QRTR in-kernel nameservice
(`net/qrtr/ns.c`):

1. `qrtr_ns_worker()` receives control packets into a single reused
   4096-byte `recv_buf` via `kernel_recvmsg()` without checking that
   `msglen >= sizeof(*pkt)` (20 bytes). If a short packet arrives on
   `qrtr_ns.sock`, `qrtr_ns_worker()` reads stale bytes from previous
   control messages (or uninitialized heap memory on the first packet)
   when parsing `pkt->cmd` and its union fields.
2. Unlike `ctrl_cmd_del_client()`, `ctrl_cmd_bye()` does not verify that
   `from->sq_port == QRTR_PORT_CTRL`, allowing any unprivileged local
   `AF_QIPCRTR` socket to send a `QRTR_TYPE_BYE` packet and purge all
   registered services for the local node.

Check `msglen < sizeof(*pkt)` in `qrtr_ns_worker()` and require
`from->sq_port == QRTR_PORT_CTRL` in `ctrl_cmd_bye()`.

Fixes: 0c2204a4ad71 ("net: qrtr: Migrate nameservice to kernel from userspace")
Assisted-by: LLM
Signed-off-by: Hui Peng <benquike@xxxxxxxxx>

---
 net/qrtr/ns.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
index bcb090ee79d4..d7e1a37f0717 100644
--- a/net/qrtr/ns.c
+++ b/net/qrtr/ns.c
@@ -347,6 +347,9 @@ static int ctrl_cmd_bye(struct sockaddr_qrtr *from)
 	iv.iov_base = &pkt;
 	iv.iov_len = sizeof(pkt);
 
+	if (from->sq_port != QRTR_PORT_CTRL)
+		return -EINVAL;
+
 	node = node_get(from->sq_node);
 	if (!node)
 		return 0;
@@ -639,6 +642,9 @@ static void qrtr_ns_worker(struct work_struct *work)
 			break;
 		}
 
+		if (msglen < sizeof(*pkt))
+			continue;
+
 		pkt = recv_buf;
 		cmd = le32_to_cpu(pkt->cmd);
 		if (cmd < ARRAY_SIZE(qrtr_ctrl_pkt_strings) &&
-- 
2.55.0.1082.g2b9226bbc0-goog