linux-cve-announce - CVE-2025-39990: bpf: Check the helper function is valid in get_helper

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Message-ID: <2025101502-CVE-2025-39990-25bc@gregkh>
Date: Wed, 15 Oct 2025 09:57:17 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39990: bpf: Check the helper function is valid in get_helper_proto

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

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

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

bpf: Check the helper function is valid in get_helper_proto

kernel test robot reported verifier bug [1] where the helper func
pointer could be NULL due to disabled config option.

As Alexei suggested we could check on that in get_helper_proto
directly. Marking tail_call helper func with BPF_PTR_POISON,
because it is unused by design.

  [1] https://lore.kernel.org/oe-lkp/202507160818.68358831-lkp@intel.com

The Linux kernel CVE team has assigned CVE-2025-39990 to this issue.


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

	Fixed in 6.12.50 with commit 3d429cb1278e995e22995ef117fa96d223a67e93
	Fixed in 6.16.10 with commit 6233715b4b714068d6c831d214a4e8792109875a
	Fixed in 6.17 with commit e4414b01c1cd9887bbde92f946c1ba94e40d6d64

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-2025-39990
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/core.c
	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/3d429cb1278e995e22995ef117fa96d223a67e93
	https://git.kernel.org/stable/c/6233715b4b714068d6c831d214a4e8792109875a
	https://git.kernel.org/stable/c/e4414b01c1cd9887bbde92f946c1ba94e40d6d64