CVE-2024-27058 tmpfs: fix race on handling dquot rbtree

2024-05-0113:00:06

Linux

github.com

linux

kernel

vulnerability

resolved

tmpfs

race

dquot

rbtree

syzkaller

reproducer

warning

dqio_sem

AI Score

6.7

Confidence

Low

EPSS

Percentile

15.5%

SSVC

Exploitation

none

Automatable

Technical Impact

partial

JSON

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

tmpfs: fix race on handling dquot rbtree

A syzkaller reproducer found a race while attempting to remove dquot
information from the rb tree.

Fetching the rb_tree root node must also be protected by the
dqopt->dqio_sem, otherwise, giving the right timing, shmem_release_dquot()
will trigger a warning because it couldn’t find a node in the tree, when
the real reason was the root node changing before the search starts:

Thread 1 Thread 2

shmem_release_dquot() - shmem_{acquire,release}_dquot()
fetch ROOT - Fetch ROOT
```
  			- acquire dqio_sem
```

wait dqio_sem

  			- do something, triger a tree rebalance
  			- release dqio_sem

acquire dqio_sem
start searching for the node, but
from the wrong location, missing
the node, and triggering a warning.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "mm/shmem_quota.c"
    ],
    "versions": [
      {
        "version": "eafc474e2029",
        "lessThan": "c7077f43f30d",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "eafc474e2029",
        "lessThan": "617d55b90e73",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "eafc474e2029",
        "lessThan": "f82f184874d2",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "eafc474e2029",
        "lessThan": "0a69b6b3a026",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "mm/shmem_quota.c"
    ],
    "versions": [
      {
        "version": "6.6",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "6.6",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.24",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.7.12",
        "lessThanOrEqual": "6.7.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.8.3",
        "lessThanOrEqual": "6.8.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]