linux-cve-announce - CVE-2022-49873: bpf: Fix wrong reg type conversion in release

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Message-ID: <2025050151-CVE-2022-49873-2733@gregkh>
Date: Thu,  1 May 2025 16:11:03 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-49873: bpf: Fix wrong reg type conversion in release_reference()

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

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

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

bpf: Fix wrong reg type conversion in release_reference()

Some helper functions will allocate memory. To avoid memory leaks, the
verifier requires the eBPF program to release these memories by calling
the corresponding helper functions.

When a resource is released, all pointer registers corresponding to the
resource should be invalidated. The verifier use release_references() to
do this job, by apply  __mark_reg_unknown() to each relevant register.

It will give these registers the type of SCALAR_VALUE. A register that
will contain a pointer value at runtime, but of type SCALAR_VALUE, which
may allow the unprivileged user to get a kernel pointer by storing this
register into a map.

Using __mark_reg_not_init() while NOT allow_ptr_leaks can mitigate this
problem.

The Linux kernel CVE team has assigned CVE-2022-49873 to this issue.


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

	Issue introduced in 4.20 with commit fd978bf7fd312581a7ca454a991f0ffb34c4204b and fixed in 5.10.155 with commit cedd4f01f67be94735f15123158f485028571037
	Issue introduced in 4.20 with commit fd978bf7fd312581a7ca454a991f0ffb34c4204b and fixed in 5.15.79 with commit 466ce46f251dfb259a8cbaa895ab9edd6fb56240
	Issue introduced in 4.20 with commit fd978bf7fd312581a7ca454a991f0ffb34c4204b and fixed in 6.0.9 with commit ae5ccad6c711db0f2ca1231be051935dd128b8f5
	Issue introduced in 4.20 with commit fd978bf7fd312581a7ca454a991f0ffb34c4204b and fixed in 6.1 with commit f1db20814af532f85e091231223e5e4818e8464b

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-2022-49873
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/cedd4f01f67be94735f15123158f485028571037
	https://git.kernel.org/stable/c/466ce46f251dfb259a8cbaa895ab9edd6fb56240
	https://git.kernel.org/stable/c/ae5ccad6c711db0f2ca1231be051935dd128b8f5
	https://git.kernel.org/stable/c/f1db20814af532f85e091231223e5e4818e8464b