Subject: CVE-2021-47134: efi/fdt: fix panic when no valid fdt found

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

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

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

efi/fdt: fix panic when no valid fdt found

setup_arch() would invoke efi_init()->efi_get_fdt_params(). If no
valid fdt found then initial_boot_params will be null. So we
should stop further fdt processing here. I encountered this
issue on risc-v.

The Linux kernel CVE team has assigned CVE-2021-47134 to this issue.

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

	Issue introduced in 5.10 with commit b91540d52a08 and fixed in 5.10.43 with commit 5148066edbdc
	Issue introduced in 5.10 with commit b91540d52a08 and fixed in 5.12.10 with commit 8a7e8b4e5631
	Issue introduced in 5.10 with commit b91540d52a08 and fixed in 5.13 with commit 668a84c1bfb2

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-2021-47134
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:
	drivers/firmware/efi/fdtparams.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/5148066edbdc89c6fe5bc419c31a5c22e5f83bdb
	https://git.kernel.org/stable/c/8a7e8b4e5631a03ea2fee27957857a56612108ca
	https://git.kernel.org/stable/c/668a84c1bfb2b3fd5a10847825a854d63fac7baa