---
id: CVE-2022-50334
title: 'hugetlbfs: fix null-ptr-deref in hugetlbfs_parse_param()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  hugetlbfs: fix null-ptr-deref in hugetlbfs_parse_param()

  Syzkaller reports a null-ptr-deref bug as follows:
  ======================================================
  KASA…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 <
    fa71639873518e3587632ae58e25e4a96b57fa90
  - >-
    Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 <
    dcd28191be9bbf307ba51a5b485773a55b0037c4
  - >-
    Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 <
    9a8862820cbf1f18dca4f3b4c289d88561b3a384
  - >-
    Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 <
    965e8f8ae0f642b5528f5a82b7bcaf15a659d5bd
  - >-
    Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 <
    f2207145693ae5697a7b59e2add4b92f9e5b0e3c
  - >-
    Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 <
    26215b7ee923b9251f7bb12c4e5f09dc465d35f2
  - Linux 5.1
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T20:10:15.500301Z'
published: '2025-09-15'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T20:10:35.956Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2022-50334'
references:
  - url: 'https://git.kernel.org/stable/c/fa71639873518e3587632ae58e25e4a96b57fa90'
  - url: 'https://git.kernel.org/stable/c/dcd28191be9bbf307ba51a5b485773a55b0037c4'
  - url: 'https://git.kernel.org/stable/c/9a8862820cbf1f18dca4f3b4c289d88561b3a384'
  - url: 'https://git.kernel.org/stable/c/965e8f8ae0f642b5528f5a82b7bcaf15a659d5bd'
  - url: 'https://git.kernel.org/stable/c/f2207145693ae5697a7b59e2add4b92f9e5b0e3c'
  - url: 'https://git.kernel.org/stable/c/26215b7ee923b9251f7bb12c4e5f09dc465d35f2'
tags:
  - cve.org
epss: 0.0016
epssPercentile: 0.05155
ingestedAt: '2026-11-05T22:38:31.728Z'
---

## Overview

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

hugetlbfs: fix null-ptr-deref in hugetlbfs_parse_param()

Syzkaller reports a null-ptr-deref bug as follows:
======================================================
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
RIP: 0010:hugetlbfs_parse_param+0x1dd/0x8e0 fs/hugetlbfs/inode.c:1380
[...]
Call Trace:
 <TASK>
 vfs_parse_fs_param fs/fs_context.c:148 [inline]
 vfs_parse_fs_param+0x1f9/0x3c0 fs/fs_context.c:129
 vfs_parse_fs_string+0xdb/0x170 fs/fs_context.c:191
 generic_parse_monolithic+0x16f/0x1f0 fs/fs_context.c:231
 do_new_mount fs/namespace.c:3036 [inline]
 path_mount+0x12de/0x1e20 fs/namespace.c:3370
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount fs/namespace.c:3568 [inline]
 __x64_sys_mount+0x27f/0x300 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
 [...]
 </TASK>
======================================================

According to commit "vfs: parse: deal with zero length string value",
kernel will set the param->string to null pointer in vfs_parse_fs_string()
if fs string has zero length.

Yet the problem is that, hugetlbfs_parse_param() will dereference the
param->string, without checking whether it is a null pointer.  To be more
specific, if hugetlbfs_parse_param() parses an illegal mount parameter,
such as "size=,", kernel will constructs struct fs_parameter with null
pointer in vfs_parse_fs_string(), then passes this struct fs_parameter to
hugetlbfs_parse_param(), which triggers the above null-ptr-deref bug.

This patch solves it by adding sanity check on param->string
in hugetlbfs_parse_param().

## Affected

- `Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 < fa71639873518e3587632ae58e25e4a96b57fa90`
- `Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 < dcd28191be9bbf307ba51a5b485773a55b0037c4`
- `Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 < 9a8862820cbf1f18dca4f3b4c289d88561b3a384`
- `Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 < 965e8f8ae0f642b5528f5a82b7bcaf15a659d5bd`
- `Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 < f2207145693ae5697a7b59e2add4b92f9e5b0e3c`
- `Linux >= 32021982a324dce93b4ae00c06213bf45fb319c8 < 26215b7ee923b9251f7bb12c4e5f09dc465d35f2`
- `Linux 5.1`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.