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

Ivan Pravdin
2025-07-17T04:32:59Z

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#syz test

Ivan Pravdin

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diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
index f7d8c3c00655..2fef08254d78 100644
--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -380,6 +380,28 @@ 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;
+
+ 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 +456,8 @@ 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);
+ if (!IS_ERR_OR_NULL(hdev->debugfs))
+ vhci_debugfs_init(data);

hci_skb_pkt_type(skb) = HCI_VENDOR_PKT;

@@ -651,6 +659,21 @@ static int vhci_open(struct inode *inode, struct file *file)
return 0;
}

+static void vhci_debugfs_remove(struct hci_dev *hdev)
+{
+ 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;
@@ -662,6 +685,8 @@ static int vhci_release(struct inode *inode, struct file *file)
hdev = data->hdev;

if (hdev) {
+ if (!IS_ERR_OR_NULL(hdev->debugfs))
+ vhci_debugfs_remove(hdev);
hci_unregister_dev(hdev);
hci_free_dev(hdev);
}
diff --git a/net/bluetooth/coredump.c b/net/bluetooth/coredump.c
index 819eacb38762..720cb79adf96 100644
--- a/net/bluetooth/coredump.c
+++ b/net/bluetooth/coredump.c
@@ -249,15 +249,15 @@ 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);
-
/* Send a copy to monitor as a diagnostic packet */
skb = bt_skb_alloc(size, GFP_ATOMIC);
if (skb) {
skb_put_data(skb, hdev->dump.head, size);
hci_recv_diag(hdev, skb);
}
+
+ /* Emit a devcoredump with the available data */
+ dev_coredumpv(&hdev->dev, hdev->dump.head, size, GFP_KERNEL);
}

static void hci_devcd_handle_pkt_complete(struct hci_dev *hdev,