An open debugfs file retains lowpan_control_fops in the debugfs proxy state. However, lowpan_control_fops has no .owner set to THIS_MODULE. As a result, full_proxy_open_regular() calls fops_get() which succeeds without taking a reference to the bluetooth_6lowpan module. With CONFIG_BT_6LOWPAN=m, a userspace process can keep the debugfs file descriptor for 6lowpan_control open across module unload (delete_module / rmmod bluetooth_6lowpan). When the process subsequently closes the file descriptor, full_proxy_release() accesses the already freed and unmapped lowpan_control_fops table, causing a kernel page fault or oops. The issue was discovered via manual code audit of net/bluetooth/6lowpan.c. Set .owner = THIS_MODULE on lowpan_control_fops so that debugfs pins the module until all open file descriptors have finished. Fixes: 6b8d4a6a0314 ("Bluetooth: 6LoWPAN: Use connected oriented channel instead of fixed one") Cc: stable@vger.kernel.org Signed-off-by: Bui Viet Dung --- net/bluetooth/6lowpan.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/bluetooth/6lowpan.c b/net/bluetooth/6lowpan.c index 30f4afa18bc8..20fb20eea8e7 100644 --- a/net/bluetooth/6lowpan.c +++ b/net/bluetooth/6lowpan.c @@ -1209,6 +1209,7 @@ static int lowpan_control_open(struct inode *inode, struct file *file) } static const struct file_operations lowpan_control_fops = { + .owner = THIS_MODULE, .open = lowpan_control_open, .read = seq_read, .write = lowpan_control_write, -- 2.43.0