CVE-2026-46252: regulator: core: fix locking in regulator_resolve_supply() error path

CVE-2026-46252: regulator: core: fix locking in regulator_resolve_supply() error path

[Greg Kroah-Hartman]

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

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

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

regulator: core: fix locking in regulator_resolve_supply() error path

If late enabling of a supply regulator fails in
regulator_resolve_supply(), the code currently triggers a lockdep
warning:

    WARNING: drivers/regulator/core.c:2649 at _regulator_put+0x80/0xa0, CPU#6: kworker/u32:4/596
    ...
    Call trace:
     _regulator_put+0x80/0xa0 (P)
     regulator_resolve_supply+0x7cc/0xbe0
     regulator_register_resolve_supply+0x28/0xb8

as the regulator_list_mutex must be held when calling _regulator_put().

To solve this, simply switch to using regulator_put().

While at it, we should also make sure that no concurrent access happens
to our rdev while we clear out the supply pointer. Add appropriate
locking to ensure that.

While the code in question will be removed altogether in a follow-up
commit, I believe it is still beneficial to have this corrected before
removal for future reference.

The Linux kernel CVE team has assigned CVE-2026-46252 to this issue.


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

	Issue introduced in 4.2 with commit 36a1f1b6ddc6d1442424e29548e790633ca39c7b and fixed in 6.19.4 with commit c66e0db0f37290b53c57994f998bb55590364fd0
	Issue introduced in 4.2 with commit 36a1f1b6ddc6d1442424e29548e790633ca39c7b and fixed in 7.0 with commit 497330b203d2c59c5ff3fa4c34d14494d7203bc3

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-2026-46252
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/regulator/core.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/c66e0db0f37290b53c57994f998bb55590364fd0
	https://git.kernel.org/stable/c/497330b203d2c59c5ff3fa4c34d14494d7203bc3