linux-cve-announce - CVE-2022-50631: RISC-V: kexec: Fix memory leak of fdt buffer

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Message-ID: <2025120931-CVE-2022-50631-ee18@gregkh>
Date: Tue,  9 Dec 2025 09:01:32 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50631: RISC-V: kexec: Fix memory leak of fdt buffer

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

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

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

RISC-V: kexec: Fix memory leak of fdt buffer

This is reported by kmemleak detector:

unreferenced object 0xff60000082864000 (size 9588):
  comm "kexec", pid 146, jiffies 4294900634 (age 64.788s)
  hex dump (first 32 bytes):
    d0 0d fe ed 00 00 12 ed 00 00 00 48 00 00 11 40  ...........H...@
    00 00 00 28 00 00 00 11 00 00 00 02 00 00 00 00  ...(............
  backtrace:
    [<00000000f95b17c4>] kmemleak_alloc+0x34/0x3e
    [<00000000b9ec8e3e>] kmalloc_order+0x9c/0xc4
    [<00000000a95cf02e>] kmalloc_order_trace+0x34/0xb6
    [<00000000f01e68b4>] __kmalloc+0x5c2/0x62a
    [<000000002bd497b2>] kvmalloc_node+0x66/0xd6
    [<00000000906542fa>] of_kexec_alloc_and_setup_fdt+0xa6/0x6ea
    [<00000000e1166bde>] elf_kexec_load+0x206/0x4ec
    [<0000000036548e09>] kexec_image_load_default+0x40/0x4c
    [<0000000079fbe1b4>] sys_kexec_file_load+0x1c4/0x322
    [<0000000040c62c03>] ret_from_syscall+0x0/0x2

In elf_kexec_load(), a buffer is allocated via kvmalloc() to store fdt.
While it's not freed back to system when kexec kernel is reloaded or
unloaded.  Then memory leak is caused.  Fix it by introducing riscv
specific function arch_kimage_file_post_load_cleanup(), and freeing the
buffer there.

The Linux kernel CVE team has assigned CVE-2022-50631 to this issue.


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

	Issue introduced in 5.19 with commit 6261586e0c91db14c34f894f4bc48f2300cff1d4 and fixed in 6.0.18 with commit c66ad198b6497dee8f45d7ed5c03629c4525c7d0
	Issue introduced in 5.19 with commit 6261586e0c91db14c34f894f4bc48f2300cff1d4 and fixed in 6.1.4 with commit dc387c34d8dd10b02a333df098f8fd9bba177a45
	Issue introduced in 5.19 with commit 6261586e0c91db14c34f894f4bc48f2300cff1d4 and fixed in 6.2 with commit 96df59b1ae23f5c11698c3c2159aeb2ecd4944a4

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-2022-50631
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/riscv/include/asm/kexec.h
	arch/riscv/kernel/elf_kexec.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/c66ad198b6497dee8f45d7ed5c03629c4525c7d0
	https://git.kernel.org/stable/c/dc387c34d8dd10b02a333df098f8fd9bba177a45
	https://git.kernel.org/stable/c/96df59b1ae23f5c11698c3c2159aeb2ecd4944a4