CVE-2021-47342 ext4: fix possible UAF when remounting r/o a mmp-protected file system

2024-05-2114:35:49

Linux

github.com

linux kernel

ext4

vulnerability

uaf

remounting

mmp-protected

memory leak

6.8 Medium

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

15.6%

JSON

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

ext4: fix possible UAF when remounting r/o a mmp-protected file system

After commit 618f003199c6 (“ext4: fix memory leak in
ext4_fill_super”), after the file system is remounted read-only, there
is a race where the kmmpd thread can exit, causing sbi->s_mmp_tsk to
point at freed memory, which the call to ext4_stop_mmpd() can trip
over.

Fix this by only allowing kmmpd() to exit when it is stopped via
ext4_stop_mmpd().

Bug-Report-Link: <[email protected]>

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/ext4/mmp.c",
      "fs/ext4/super.c"
    ],
    "versions": [
      {
        "version": "1da177e4c3f4",
        "lessThan": "b663890d8544",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "7ed572cdf110",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "1da177e4c3f4",
        "lessThan": "61bb4a1c417e",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "fs/ext4/mmp.c",
      "fs/ext4/super.c"
    ],
    "versions": [
      {
        "version": "5.10.77",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.13.3",
        "lessThanOrEqual": "5.13.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.14",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]