Subject: CVE-2024-43862: net: wan: fsl_qmc_hdlc: Convert carrier_lock spinlock to a mutex

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

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

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

net: wan: fsl_qmc_hdlc: Convert carrier_lock spinlock to a mutex

The carrier_lock spinlock protects the carrier detection. While it is
held, framer_get_status() is called which in turn takes a mutex.
This is not correct and can lead to a deadlock.

A run with PROVE_LOCKING enabled detected the issue:
  [ BUG: Invalid wait context ]
  ...
  c204ddbc (&framer->mutex){+.+.}-{3:3}, at: framer_get_status+0x40/0x78
  other info that might help us debug this:
  context-{4:4}
  2 locks held by ifconfig/146:
  #0: c0926a38 (rtnl_mutex){+.+.}-{3:3}, at: devinet_ioctl+0x12c/0x664
  #1: c2006a40 (&qmc_hdlc->carrier_lock){....}-{2:2}, at: qmc_hdlc_framer_set_carrier+0x30/0x98

Avoid the spinlock usage and convert carrier_lock to a mutex.

The Linux kernel CVE team has assigned CVE-2024-43862 to this issue.

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

	Issue introduced in 6.9 with commit 54762918ca85 and fixed in 6.10.4 with commit f223d2b4acb7
	Issue introduced in 6.9 with commit 54762918ca85 and fixed in 6.11 with commit c4d6a347ba7b

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-2024-43862
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/net/wan/fsl_qmc_hdlc.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/f223d2b4acb7a45a6e0581cb380e1af1a6dc7ab9
	https://git.kernel.org/stable/c/c4d6a347ba7babdf9d90a0eb24048c266cae0532