Subject: CVE-2022-48929: bpf: Fix crash due to out of bounds access into reg2btf_ids.

From: Greg Kroah-Hartman <[email-masked]>

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

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

bpf: Fix crash due to out of bounds access into reg2btf_ids.

When commit e6ac2450d6de ("bpf: Support bpf program calling kernel function") added
kfunc support, it defined reg2btf_ids as a cheap way to translate the verifier
reg type to the appropriate btf_vmlinux BTF ID, however
commit c25b2ae13603 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL")
moved the __BPF_REG_TYPE_MAX from the last member of bpf_reg_type enum to after
the base register types, and defined other variants using type flag
composition. However, now, the direct usage of reg->type to index into
reg2btf_ids may no longer fall into __BPF_REG_TYPE_MAX range, and hence lead to
out of bounds access and kernel crash on dereference of bad pointer.

The Linux kernel CVE team has assigned CVE-2022-48929 to this issue.

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

	Issue introduced in 5.15.15 with commit e8efe8369944 and fixed in 5.15.37 with commit 8c39925e98d4
	Issue introduced in 5.16.1 with commit 931e56be527f and fixed in 5.16.12 with commit f0ce1bc9e023
	Issue introduced in 5.10.92 with commit 35ab8c9085b0
	Issue introduced in 5.16.11 with commit 77459bc4d5e2

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-2022-48929
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/btf.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/8c39925e98d498b9531343066ef82ae39e41adae
	https://git.kernel.org/stable/c/f0ce1bc9e0235dd7412240be493d7ea65ed9eadc
	https://git.kernel.org/stable/c/45ce4b4f9009102cd9f581196d480a59208690c1