Subject: CVE-2024-41062: bluetooth/l2cap: sync sock recv cb and release

From: Greg Kroah-Hartman <[email-masked]>

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

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

bluetooth/l2cap: sync sock recv cb and release

The problem occurs between the system call to close the sock and hci_rx_work,
where the former releases the sock and the latter accesses it without lock protection.

           CPU0                       CPU1
           ----                       ----
           sock_close                 hci_rx_work
	   l2cap_sock_release         hci_acldata_packet
	   l2cap_sock_kill            l2cap_recv_frame
	   sk_free                    l2cap_conless_channel
	                              l2cap_sock_recv_cb

If hci_rx_work processes the data that needs to be received before the sock is
closed, then everything is normal; Otherwise, the work thread may access the
released sock when receiving data.

Add a chan mutex in the rx callback of the sock to achieve synchronization between
the sock release and recv cb.

Sock is dead, so set chan data to NULL, avoid others use invalid sock pointer.

The Linux kernel CVE team has assigned CVE-2024-41062 to this issue.

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

	Fixed in 6.1.101 with commit 605572e64cd9
	Fixed in 6.6.42 with commit b803f30ea23e
	Fixed in 6.9.11 with commit 3b732449b781
	Fixed in 6.10 with commit 89e856e124f9

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-2024-41062
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:
	net/bluetooth/l2cap_sock.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/605572e64cd9cebb05ed609d96cff05b50d18cdf
	https://git.kernel.org/stable/c/b803f30ea23e0968b6c8285c42adf0d862ab2bf6
	https://git.kernel.org/stable/c/3b732449b78183d17178db40be3a4401cf3cd629
	https://git.kernel.org/stable/c/89e856e124f9ae548572c56b1b70c2255705f8fe