vulnerability

Red Hat: CVE-2022-50091: kernel: locking/csd_lock: Change csdlock_debug from early_param to __setup

Severity
7
CVSS
(AV:L/AC:M/Au:S/C:C/I:C/A:C)
Published
Jun 18, 2025
Added
Jul 9, 2025
Modified
Jul 21, 2025

Description

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

locking/csd_lock: Change csdlock_debug from early_param to __setup

The csdlock_debug kernel-boot parameter is parsed by the
early_param() function csdlock_debug(). If set, csdlock_debug()
invokes static_branch_enable() to enable csd_lock_wait feature, which
triggers a panic on arm64 for kernels built with CONFIG_SPARSEMEM=y and
CONFIG_SPARSEMEM_VMEMMAP=n.

With CONFIG_SPARSEMEM_VMEMMAP=n, __nr_to_section is called in
static_key_enable() and returns NULL, resulting in a NULL dereference
because mem_section is initialized only later in sparse_init().

This is also a problem for powerpc because early_param() functions
are invoked earlier than jump_label_init(), also resulting in
static_key_enable() failures. These failures cause the warning "static
key 'xxx' used before call to jump_label_init()".

Thus, early_param is too early for csd_lock_wait to run
static_branch_enable(), so changes it to __setup to fix these.

Solution

no-fix-redhat-rpm-package
Title
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