Subject: CVE-2024-50077: Bluetooth: ISO: Fix multiple init when debugfs is disabled

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

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

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

Bluetooth: ISO: Fix multiple init when debugfs is disabled

If bt_debugfs is not created successfully, which happens if either
CONFIG_DEBUG_FS or CONFIG_DEBUG_FS_ALLOW_ALL is unset, then iso_init()
returns early and does not set iso_inited to true. This means that a
subsequent call to iso_init() will result in duplicate calls to
proto_register(), bt_sock_register(), etc.

With CONFIG_LIST_HARDENED and CONFIG_BUG_ON_DATA_CORRUPTION enabled, the
duplicate call to proto_register() triggers this BUG():

  list_add double add: new=ffffffffc0b280d0, prev=ffffffffbab56250,
    next=ffffffffc0b280d0.
  ------------[ cut here ]------------
  kernel BUG at lib/list_debug.c:35!
  Oops: invalid opcode: 0000 [#1] PREEMPT SMP PTI
  CPU: 2 PID: 887 Comm: bluetoothd Not tainted 6.10.11-1-ao-desktop #1
  RIP: 0010:__list_add_valid_or_report+0x9a/0xa0
  ...
    __list_add_valid_or_report+0x9a/0xa0
    proto_register+0x2b5/0x340
    iso_init+0x23/0x150 [bluetooth]
    set_iso_socket_func+0x68/0x1b0 [bluetooth]
    kmem_cache_free+0x308/0x330
    hci_sock_sendmsg+0x990/0x9e0 [bluetooth]
    __sock_sendmsg+0x7b/0x80
    sock_write_iter+0x9a/0x110
    do_iter_readv_writev+0x11d/0x220
    vfs_writev+0x180/0x3e0
    do_writev+0xca/0x100
  ...

This change removes the early return. The check for iso_debugfs being
NULL was unnecessary, it is always NULL when iso_inited is false.

The Linux kernel CVE team has assigned CVE-2024-50077 to this issue.

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

	Issue introduced in 6.0 with commit ccf74f2390d6 and fixed in 6.1.114 with commit fa4b832c5a6e
	Issue introduced in 6.0 with commit ccf74f2390d6 and fixed in 6.6.58 with commit 8fb8e912afb4
	Issue introduced in 6.0 with commit ccf74f2390d6 and fixed in 6.11.5 with commit adf1b179c2ff
	Issue introduced in 6.0 with commit ccf74f2390d6 and fixed in 6.12-rc4 with commit a9b7b535ba19

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-2024-50077
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/iso.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/fa4b832c5a6ec35023a1b997cf658c436619c752
	https://git.kernel.org/stable/c/8fb8e912afb4c47dec12ea9a5853e7a8db95816f
	https://git.kernel.org/stable/c/adf1b179c2ff8073c24bf87e5a605fcc5a09798b
	https://git.kernel.org/stable/c/a9b7b535ba192c6b77e6c15a4c82d853163eab8c