CVE-2026-97977: Bluetooth: btusb: Fix UAF of btusb_data by rx_work

CVE-2026-97977: Bluetooth: btusb: Fix UAF of btusb_data by rx_work

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

Bluetooth: btusb: Fix UAF of btusb_data by rx_work

btusb_close() and btusb_flush() cancel data->rx_work with the
asynchronous cancel_delayed_work(), so if btusb_rx_work() is already
running on another CPU it keeps running after the cancel returns.

btusb_disconnect() calls hci_unregister_dev(), which invokes
btusb_close(), and then frees the btusb_data. A still running
btusb_rx_work() then dereferences the freed data:

	while ((skb = skb_dequeue(&data->acl_q)))
		data->recv_acl(data->hdev, skb);

Use cancel_delayed_work_sync() instead. In btusb_close() the cancel also
has to happen after btusb_stop_traffic(), otherwise an URB completion
racing with the cancel can requeue the work right after it has been
waited for.

The Linux kernel CVE team has assigned CVE-2026-97977 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.17 with commit 800fe5ec302e1ebbf5e3f891f886deecd49c7132 and fixed in 6.12.111 with commit 472d005622525b7be155cac99dde2252b0163bd1
	Issue introduced in 5.17 with commit 800fe5ec302e1ebbf5e3f891f886deecd49c7132 and fixed in 6.18.53 with commit 93b59937bda3fffc6386c79f5544a39bc680c8e8
	Issue introduced in 5.17 with commit 800fe5ec302e1ebbf5e3f891f886deecd49c7132 and fixed in 7.2.7 with commit fa391adb9c755515a89993634745e9079e5ef37c
	Issue introduced in 5.17 with commit 800fe5ec302e1ebbf5e3f891f886deecd49c7132 and fixed in 7.3-rc3 with commit 1c12c3117639e78940959d956519c758c57d0849

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-97977
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/bluetooth/btusb.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/472d005622525b7be155cac99dde2252b0163bd1
	https://git.kernel.org/stable/c/93b59937bda3fffc6386c79f5544a39bc680c8e8
	https://git.kernel.org/stable/c/fa391adb9c755515a89993634745e9079e5ef37c
	https://git.kernel.org/stable/c/1c12c3117639e78940959d956519c758c57d0849