mbim: fix memory corruption issues

Use a common buffer that has enough headroom for the MBIM header.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

3 files changed, 19 insertions, 17 deletions

diff --git a/commands.c b/commands.c
index 869ca7c..04ca238 100644
--- a/commands.c
+++ b/commands.c
@@ -205,8 +205,8 @@ static void uqmi_print_result(struct blob_attr *data)
 
 static bool __uqmi_run_commands(struct qmi_dev *qmi, bool option)
 {
-	static char buf[2048];
 	static struct qmi_request req;
+	char *buf = qmi->buf;
 	int i;
 
 	for (i = 0; i < n_cmds; i++) {
@@ -227,7 +227,7 @@ static bool __uqmi_run_commands(struct qmi_dev *qmi, bool option)
 		}
 
 		if (res == QMI_CMD_REQUEST) {
-			qmi_request_start(qmi, &req, (void *) buf, cmds[i].handler->cb);
+			qmi_request_start(qmi, &req, cmds[i].handler->cb);
 			req.no_error_cb = true;
 			if (qmi_request_wait(qmi, &req)) {
 				uqmi_add_error(qmi_get_error_str(req.ret));
diff --git a/dev.c b/dev.c
index 9bf7ab2..4bca429 100644
--- a/dev.c
+++ b/dev.c
@@ -37,14 +37,6 @@ static const uint8_t qmi_services[__QMI_SERVICE_LAST] = {
 };
 #undef __qmi_service
 
-static struct {
-	struct mbim_command_message mbim;
-	union {
-		char buf[512];
-		struct qmi_msg msg;
-	} u;
-} __packed msgbuf;
-
 #ifdef DEBUG_PACKET
 void dump_packet(const char *prefix, void *ptr, int len)
 {
@@ -162,11 +154,12 @@ static void qmi_notify_read(struct ustream *us, int bytes)
 	}
 }
 
-int qmi_request_start(struct qmi_dev *qmi, struct qmi_request *req, struct qmi_msg *msg, request_cb cb)
+int qmi_request_start(struct qmi_dev *qmi, struct qmi_request *req, request_cb cb)
 {
+	struct qmi_msg *msg = qmi->buf;
 	int len = qmi_complete_request_message(msg);
 	uint16_t tid;
-	char *buf = (void *) msg;
+	void *buf = (void *) qmi->buf;
 
 	memset(req, 0, sizeof(*req));
 	req->ret = -1;
@@ -260,7 +253,7 @@ int qmi_service_connect(struct qmi_dev *qmi, QmiService svc, int client_id)
 	};
 	struct qmi_connect_request req;
 	int idx = qmi_get_service_idx(svc);
-	struct qmi_msg *msg = &msgbuf.u.msg;
+	struct qmi_msg *msg = qmi->buf;
 
 	if (idx < 0)
 		return -1;
@@ -270,7 +263,7 @@ int qmi_service_connect(struct qmi_dev *qmi, QmiService svc, int client_id)
 
 	if (client_id < 0) {
 		qmi_set_ctl_allocate_cid_request(msg, &creq);
-		qmi_request_start(qmi, &req.req, msg, qmi_connect_service_cb);
+		qmi_request_start(qmi, &req.req, qmi_connect_service_cb);
 		qmi_request_wait(qmi, &req.req);
 
 		if (req.req.ret)
@@ -299,14 +292,14 @@ static void __qmi_service_disconnect(struct qmi_dev *qmi, int idx)
 		)
 	};
 	struct qmi_request req;
-	struct qmi_msg *msg = &msgbuf.u.msg;
+	struct qmi_msg *msg = qmi->buf;
 
 	qmi->service_connected &= ~(1 << idx);
 	qmi->service_data[idx].client_id = -1;
 	qmi->service_data[idx].tid = 0;
 
 	qmi_set_ctl_release_cid_request(msg, &creq);
-	qmi_request_start(qmi, &req, msg, NULL);
+	qmi_request_start(qmi, &req, NULL);
 	qmi_request_wait(qmi, &req);
 }
 
@@ -347,6 +340,13 @@ int qmi_service_get_client_id(struct qmi_dev *qmi, QmiService svc)
 
 int qmi_device_open(struct qmi_dev *qmi, const char *path)
 {
+	static struct {
+		struct mbim_command_message mbim;
+		union {
+			char buf[2048];
+			struct qmi_msg msg;
+		} u;
+	} __packed msgbuf;
 	struct ustream *us = &qmi->sf.stream;
 	int fd;
 
@@ -360,6 +360,7 @@ int qmi_device_open(struct qmi_dev *qmi, const char *path)
 	ustream_fd_init(&qmi->sf, fd);
 	INIT_LIST_HEAD(&qmi->req);
 	qmi->ctl_tid = 1;
+	qmi->buf = msgbuf.u.buf;
 
 	return 0;
 }
diff --git a/uqmi.h b/uqmi.h
index 2999977..dd88151 100644
--- a/uqmi.h
+++ b/uqmi.h
@@ -87,6 +87,7 @@ struct qmi_dev {
 	uint32_t service_release_cid;
 
 	uint8_t ctl_tid;
+	void *buf;
 
 	bool is_mbim;
 };
@@ -108,7 +109,7 @@ extern bool cancel_all_requests;
 int qmi_device_open(struct qmi_dev *qmi, const char *path);
 void qmi_device_close(struct qmi_dev *qmi);
 
-int qmi_request_start(struct qmi_dev *qmi, struct qmi_request *req, struct qmi_msg *msg, request_cb cb);
+int qmi_request_start(struct qmi_dev *qmi, struct qmi_request *req, request_cb cb);
 void qmi_request_cancel(struct qmi_dev *qmi, struct qmi_request *req);
 int qmi_request_wait(struct qmi_dev *qmi, struct qmi_request *req);