linux-cve-announce - CVE-2024-56768: bpf: Fix bpf_get_smp_processor_id() on !CONFIG

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Message-ID: <2025010657-CVE-2024-56768-c835@gregkh>
Date: Mon,  6 Jan 2025 17:21:02 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56768: bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP

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

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

bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP

On x86-64 calling bpf_get_smp_processor_id() in a kernel with CONFIG_SMP
disabled can trigger the following bug, as pcpu_hot is unavailable:

 [    8.471774] BUG: unable to handle page fault for address: 00000000936a290c
 [    8.471849] #PF: supervisor read access in kernel mode
 [    8.471881] #PF: error_code(0x0000) - not-present page

Fix by inlining a return 0 in the !CONFIG_SMP case.

The Linux kernel CVE team has assigned CVE-2024-56768 to this issue.


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

	Issue introduced in 6.10 with commit 1ae6921009e5d72787e07ccc04754514ccf6bc99 and fixed in 6.12.8 with commit f4ab7d74247b0150547cf909b3f6f24ee85183df
	Issue introduced in 6.10 with commit 1ae6921009e5d72787e07ccc04754514ccf6bc99 and fixed in 6.13-rc4 with commit 23579010cf0a12476e96a5f1acdf78a9c5843657

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-2024-56768
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:
	kernel/bpf/verifier.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/f4ab7d74247b0150547cf909b3f6f24ee85183df
	https://git.kernel.org/stable/c/23579010cf0a12476e96a5f1acdf78a9c5843657