Subject: CVE-2024-46693: soc: qcom: pmic_glink: Fix race during initialization

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

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

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

soc: qcom: pmic_glink: Fix race during initialization

As pointed out by Stephen Boyd it is possible that during initialization
of the pmic_glink child drivers, the protection-domain notifiers fires,
and the associated work is scheduled, before the client registration
returns and as a result the local "client" pointer has been initialized.

The outcome of this is a NULL pointer dereference as the "client"
pointer is blindly dereferenced.

Timeline provided by Stephen:
 CPU0                               CPU1
 ----                               ----
 ucsi->client = NULL;
 devm_pmic_glink_register_client()
  client->pdr_notify(client->priv, pg->client_state)
   pmic_glink_ucsi_pdr_notify()
    schedule_work(&ucsi->register_work)
    <schedule away>
                                    pmic_glink_ucsi_register()
                                     ucsi_register()
                                      pmic_glink_ucsi_read_version()
                                       pmic_glink_ucsi_read()
                                        pmic_glink_ucsi_read()
                                         pmic_glink_send(ucsi->client)
                                         <client is NULL BAD>
 ucsi->client = client // Too late!

This code is identical across the altmode, battery manager and usci
child drivers.

Resolve this by splitting the allocation of the "client" object and the
registration thereof into two operations.

This only happens if the protection domain registry is populated at the
time of registration, which by the introduction of commit '1ebcde047c54
("soc: qcom: add pd-mapper implementation")' became much more likely.

The Linux kernel CVE team has assigned CVE-2024-46693 to this issue.

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

	Issue introduced in 6.3 with commit 58ef4ece1e41 and fixed in 6.6.49 with commit 1efdbf5323c9
	Issue introduced in 6.3 with commit 58ef4ece1e41 and fixed in 6.10.8 with commit 943b0e7cc646
	Issue introduced in 6.3 with commit 58ef4ece1e41 and fixed in 6.11 with commit 3568affcddd6

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-2024-46693
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/power/supply/qcom_battmgr.c
	drivers/soc/qcom/pmic_glink.c
	drivers/soc/qcom/pmic_glink_altmode.c
	drivers/usb/typec/ucsi/ucsi_glink.c
	include/linux/soc/qcom/pmic_glink.h

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/1efdbf5323c9360e05066049b97414405e94e087
	https://git.kernel.org/stable/c/943b0e7cc646a624bb20a68080f8f1a4a55df41c
	https://git.kernel.org/stable/c/3568affcddd68743e25aa3ec1647d9b82797757b