Merge "USB: f_qc_rndis: Prevent use-after-free for _rndis_qc"

drivers/usb/gadget/function/f_qc_rndis.c

@@ -1245,16 +1245,19 @@ usb_function *rndis_qc_bind_config_vendor(struct usb_function_instance *fi,
 	rndis->func.resume = rndis_qc_resume;
 	rndis->func.free_func = rndis_qc_free;
 
-	_rndis_qc = rndis;
-
 	status = rndis_ipa_init(&rndis_ipa_params);
 	if (status) {
 		pr_err("%s: failed to init rndis_ipa\n", __func__);
-		kfree(rndis);
-		return ERR_PTR(status);
+		goto fail;
 	}
 
+	_rndis_qc = rndis;
+
 	return &rndis->func;
+fail:
+	kfree(rndis);
+	_rndis_qc = NULL;
+	return ERR_PTR(status);
 }
 
 static struct usb_function *qcrndis_alloc(struct usb_function_instance *fi)
@@ -1264,74 +1267,116 @@ static struct usb_function *qcrndis_alloc(struct usb_function_instance *fi)
 
 static int rndis_qc_open_dev(struct inode *ip, struct file *fp)
 {
+	int ret = 0;
+	unsigned long flags;
 	pr_info("Open rndis QC driver\n");
 
+	spin_lock_irqsave(&rndis_lock, flags);
 	if (!_rndis_qc) {
 		pr_err("rndis_qc_dev not created yet\n");
-		return -ENODEV;
+		ret = -ENODEV;
+		goto fail;
 	}
 
 	if (rndis_qc_lock(&_rndis_qc->open_excl)) {
 		pr_err("Already opened\n");
-		return -EBUSY;
+		ret = -EBUSY;
+		goto fail;
 	}
 
 	fp->private_data = _rndis_qc;
-	pr_info("rndis QC file opened\n");
+fail:
+	spin_unlock_irqrestore(&rndis_lock, flags);
 
-	return 0;
+	if (!ret)
+		pr_info("rndis QC file opened\n");
+
+	return ret;
 }
 
 static int rndis_qc_release_dev(struct inode *ip, struct file *fp)
 {
-	struct f_rndis_qc	*rndis = fp->private_data;
-
+	unsigned long flags;
 	pr_info("Close rndis QC file\n");
-	rndis_qc_unlock(&rndis->open_excl);
 
+	spin_lock_irqsave(&rndis_lock, flags);
+
+	if (!_rndis_qc) {
+		pr_err("rndis_qc_dev not present\n");
+		spin_unlock_irqrestore(&rndis_lock, flags);
+		return -ENODEV;
+	}
+	rndis_qc_unlock(&_rndis_qc->open_excl);
+	spin_unlock_irqrestore(&rndis_lock, flags);
 	return 0;
 }
 
 static long rndis_qc_ioctl(struct file *fp, unsigned cmd, unsigned long arg)
 {
-	struct f_rndis_qc	*rndis = fp->private_data;
+	u8 qc_max_pkt_per_xfer = 0;
+	u32 qc_max_pkt_size = 0;
 	int ret = 0;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rndis_lock, flags);
+	if (!_rndis_qc) {
+		pr_err("rndis_qc_dev not present\n");
+		ret = -ENODEV;
+		goto fail;
+	}
+
+	qc_max_pkt_per_xfer = _rndis_qc->ul_max_pkt_per_xfer;
+	qc_max_pkt_size = _rndis_qc->max_pkt_size;
+
+	if (rndis_qc_lock(&_rndis_qc->ioctl_excl)) {
+		ret = -EBUSY;
+		goto fail;
+	}
+
+	spin_unlock_irqrestore(&rndis_lock, flags);
 
 	pr_info("Received command %d\n", cmd);
 
-	if (rndis_qc_lock(&rndis->ioctl_excl))
-		return -EBUSY;
-
 	switch (cmd) {
 	case RNDIS_QC_GET_MAX_PKT_PER_XFER:
 		ret = copy_to_user((void __user *)arg,
-					&rndis->ul_max_pkt_per_xfer,
-					sizeof(rndis->ul_max_pkt_per_xfer));
+					&qc_max_pkt_per_xfer,
+					sizeof(qc_max_pkt_per_xfer));
 		if (ret) {
 			pr_err("copying to user space failed\n");
 			ret = -EFAULT;
 		}
 		pr_info("Sent UL max packets per xfer %d\n",
-				rndis->ul_max_pkt_per_xfer);
+				qc_max_pkt_per_xfer);
 		break;
 	case RNDIS_QC_GET_MAX_PKT_SIZE:
 		ret = copy_to_user((void __user *)arg,
-					&rndis->max_pkt_size,
-					sizeof(rndis->max_pkt_size));
+					&qc_max_pkt_size,
+					sizeof(qc_max_pkt_size));
 		if (ret) {
 			pr_err("copying to user space failed\n");
 			ret = -EFAULT;
 		}
 		pr_debug("Sent max packet size %d\n",
-				rndis->max_pkt_size);
+				qc_max_pkt_size);
 		break;
 	default:
 		pr_err("Unsupported IOCTL\n");
 		ret = -EINVAL;
 	}
 
-	rndis_qc_unlock(&rndis->ioctl_excl);
+	spin_lock_irqsave(&rndis_lock, flags);
 
+	if (!_rndis_qc) {
+		pr_err("rndis_qc_dev not present\n");
+		ret = -ENODEV;
+		goto fail;
+	}
+
+	rndis_qc_unlock(&_rndis_qc->ioctl_excl);
+
+fail:
+	spin_unlock_irqrestore(&rndis_lock, flags);
 	return ret;
 }
 
@@ -1385,11 +1430,11 @@ static int qcrndis_set_inst_name(struct usb_function_instance *fi,
 		return -ENOMEM;
 	}
 
+	spin_lock_init(&rndis_lock);
 	opts->rndis = rndis;
 	ret = misc_register(&rndis_qc_device);
 	if (ret)
 		pr_err("rndis QC driver failed to register\n");
-	spin_lock_init(&rndis_lock);
 
 	ret = ipa_data_setup(USB_IPA_FUNC_RNDIS);
 	if (ret) {