linux-cve-announce - CVE-2022-50168: bpf, x86: fix freeing of not-finalized bpf_prog

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Message-ID: <2025061828-CVE-2022-50168-bf75@gregkh>
Date: Wed, 18 Jun 2025 13:03:53 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50168: bpf, x86: fix freeing of not-finalized bpf_prog_pack

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

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

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

bpf, x86: fix freeing of not-finalized bpf_prog_pack

syzbot reported a few issues with bpf_prog_pack [1], [2]. This only happens
with multiple subprogs. In jit_subprogs(), we first call bpf_int_jit_compile()
on each sub program. And then, we call it on each sub program again. jit_data
is not freed in the first call of bpf_int_jit_compile(). Similarly we don't
call bpf_jit_binary_pack_finalize() in the first call of bpf_int_jit_compile().

If bpf_int_jit_compile() failed for one sub program, we will call
bpf_jit_binary_pack_finalize() for this sub program. However, we don't have a
chance to call it for other sub programs. Then we will hit "goto out_free" in
jit_subprogs(), and call bpf_jit_free on some subprograms that haven't got
bpf_jit_binary_pack_finalize() yet.

At this point, bpf_jit_binary_pack_free() is called and the whole 2MB page is
freed erroneously.

Fix this with a custom bpf_jit_free() for x86_64, which calls
bpf_jit_binary_pack_finalize() if necessary. Also, with custom
bpf_jit_free(), bpf_prog_aux->use_bpf_prog_pack is not needed any more,
remove it.

[1] https://syzkaller.appspot.com/bug?extid=2f649ec6d2eea1495a8f
[2] https://syzkaller.appspot.com/bug?extid=87f65c75f4a72db05445

The Linux kernel CVE team has assigned CVE-2022-50168 to this issue.

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

	Issue introduced in 5.18 with commit 1022a5498f6f745c3b5fd3f050a5e11e7ca354f0 and fixed in 5.18.18 with commit f91ce608a79c0db3e72bd63c23e011a9ebc31505
	Issue introduced in 5.18 with commit 1022a5498f6f745c3b5fd3f050a5e11e7ca354f0 and fixed in 5.19.2 with commit 60e66074812dde9cde3d99cdd3caa9e40f1a4516
	Issue introduced in 5.18 with commit 1022a5498f6f745c3b5fd3f050a5e11e7ca354f0 and fixed in 6.0 with commit 1d5f82d9dd477d5c66e0214a68c3e4f308eadd6d

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-2022-50168
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:
	arch/x86/net/bpf_jit_comp.c
	include/linux/bpf.h
	include/linux/filter.h
	kernel/bpf/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/f91ce608a79c0db3e72bd63c23e011a9ebc31505
	https://git.kernel.org/stable/c/60e66074812dde9cde3d99cdd3caa9e40f1a4516
	https://git.kernel.org/stable/c/1d5f82d9dd477d5c66e0214a68c3e4f308eadd6d