Re: [syzbot] Re: [syzbot] [bluetooth?] KASAN: vmalloc-out-of-bounds Read in hci_devcd_dump

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Subject: Re: [syzbot] [bluetooth?] KASAN: vmalloc-out-of-bounds Read in hci_devcd_dump
Author: ipravdin.official@gmail.com

#syz test

diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
index 59f4d7bdffdc..82a1088cd662 100644
--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -380,6 +380,31 @@ static const struct file_operations force_devcoredump_fops = {
 	.write		= force_devcd_write,
 };
 
+static void vhci_debugfs_init(struct vhci_data *data)
+{
+	struct hci_dev *hdev = data->hdev;
+
+	if (!hdev->debugfs)
+		return;
+
+	debugfs_create_file("force_suspend", 0644, hdev->debugfs, data,
+			    &force_suspend_fops);
+
+	debugfs_create_file("force_wakeup", 0644, hdev->debugfs, data,
+			    &force_wakeup_fops);
+
+	if (IS_ENABLED(CONFIG_BT_MSFTEXT))
+		debugfs_create_file("msft_opcode", 0644, hdev->debugfs, data,
+				    &msft_opcode_fops);
+
+	if (IS_ENABLED(CONFIG_BT_AOSPEXT))
+		debugfs_create_file("aosp_capable", 0644, hdev->debugfs, data,
+				    &aosp_capable_fops);
+
+	debugfs_create_file("force_devcoredump", 0644, hdev->debugfs, data,
+			    &force_devcoredump_fops);
+}
+
 static int __vhci_create_device(struct vhci_data *data, __u8 opcode)
 {
 	struct hci_dev *hdev;
@@ -434,22 +459,9 @@ static int __vhci_create_device(struct vhci_data *data, __u8 opcode)
 		return -EBUSY;
 	}
 
-	debugfs_create_file("force_suspend", 0644, hdev->debugfs, data,
-			    &force_suspend_fops);
-
-	debugfs_create_file("force_wakeup", 0644, hdev->debugfs, data,
-			    &force_wakeup_fops);
-
-	if (IS_ENABLED(CONFIG_BT_MSFTEXT))
-		debugfs_create_file("msft_opcode", 0644, hdev->debugfs, data,
-				    &msft_opcode_fops);
-
-	if (IS_ENABLED(CONFIG_BT_AOSPEXT))
-		debugfs_create_file("aosp_capable", 0644, hdev->debugfs, data,
-				    &aosp_capable_fops);
-
-	debugfs_create_file("force_devcoredump", 0644, hdev->debugfs, data,
-			    &force_devcoredump_fops);
+#ifdef CONFIG_DEBUG_FS
+	vhci_debugfs_init(data);
+#endif
 
 	hci_skb_pkt_type(skb) = HCI_VENDOR_PKT;
 
@@ -651,6 +663,26 @@ static int vhci_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static void vhci_debugfs_remove(struct vhci_data *data)
+{
+	struct hci_dev *hdev = data->hdev;
+
+	if (!hdev->debugfs)
+		return;
+
+	debugfs_lookup_and_remove("force_suspend", hdev->debugfs);
+
+	debugfs_lookup_and_remove("force_wakeup", hdev->debugfs);
+
+	if (IS_ENABLED(CONFIG_BT_MSFTEXT))
+		debugfs_lookup_and_remove("msft_opcode", hdev->debugfs);
+
+	if (IS_ENABLED(CONFIG_BT_AOSPEXT))
+		debugfs_lookup_and_remove("aosp_capable", hdev->debugfs);
+
+	debugfs_lookup_and_remove("force_devcoredump", hdev->debugfs);
+}
+
 static int vhci_release(struct inode *inode, struct file *file)
 {
 	struct vhci_data *data = file->private_data;
@@ -661,6 +693,10 @@ static int vhci_release(struct inode *inode, struct file *file)
 
 	hdev = data->hdev;
 
+#ifdef CONFIG_DEBUG_FS
+	vhci_debugfs_remove(data);
+#endif
+
 	if (hdev) {
 		hci_unregister_dev(hdev);
 		hci_free_dev(hdev);
diff --git a/net/bluetooth/coredump.c b/net/bluetooth/coredump.c
index 819eacb38762..908ad0d242c3 100644
--- a/net/bluetooth/coredump.c
+++ b/net/bluetooth/coredump.c
@@ -243,6 +243,7 @@ static void hci_devcd_handle_pkt_pattern(struct hci_dev *hdev,
 static void hci_devcd_dump(struct hci_dev *hdev)
 {
 	struct sk_buff *skb;
+	char* coredump;
 	u32 size;
 
 	bt_dev_dbg(hdev, "state %d", hdev->dump.state);
@@ -250,7 +251,11 @@ static void hci_devcd_dump(struct hci_dev *hdev)
 	size = hdev->dump.tail - hdev->dump.head;
 
 	/* Emit a devcoredump with the available data */
-	dev_coredumpv(&hdev->dev, hdev->dump.head, size, GFP_KERNEL);
+	coredump = vmalloc(size);
+	if (coredump) {
+		memcpy(coredump, hdev->dump.head, size);
+		dev_coredumpv(&hdev->dev, coredump, size, GFP_KERNEL);
+	}
 
 	/* Send a copy to monitor as a diagnostic packet */
 	skb = bt_skb_alloc(size, GFP_ATOMIC);

Ivan Pravdin