CVE-2024-39486 (GCVE-0-2024-39486)
Vulnerability from cvelistv5
Published
2024-07-06 09:25
Modified
2026-05-23 15:50
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: drm/drm_file: Fix pid refcounting race <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de> filp->pid is supposed to be a refcounted pointer; however, before this patch, drm_file_update_pid() only increments the refcount of a struct pid after storing a pointer to it in filp->pid and dropping the dev->filelist_mutex, making the following race possible: process A process B ========= ========= begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid B>, 1) mutex_unlock(&dev->filelist_mutex) begin drm_file_update_pid mutex_lock(&dev->filelist_mutex) rcu_replace_pointer(filp->pid, <pid A>, 1) mutex_unlock(&dev->filelist_mutex) get_pid(<pid A>) synchronize_rcu() put_pid(<pid B>) *** pid B reaches refcount 0 and is freed here *** get_pid(<pid B>) *** UAF *** synchronize_rcu() put_pid(<pid A>) As far as I know, this race can only occur with CONFIG_PREEMPT_RCU=y because it requires RCU to detect a quiescent state in code that is not explicitly calling into the scheduler. This race leads to use-after-free of a "struct pid". It is probably somewhat hard to hit because process A has to pass through a synchronize_rcu() operation while process B is between mutex_unlock() and get_pid(). Fix it by ensuring that by the time a pointer to the current task's pid is stored in the file, an extra reference to the pid has been taken. This fix also removes the condition for synchronize_rcu(); I think that optimization is unnecessary complexity, since in that case we would usually have bailed out on the lockless check above.
References
Impacted products
Vendor Product Version
Linux Linux Version: 031ddd28008971cce0b5626379b910d0a05fb4dd
Version: 1c7a387ffef894b1ab3942f0482dac7a6e0a909c
Version: 1c7a387ffef894b1ab3942f0482dac7a6e0a909c
Version: 6.6.9   ≤
Create a notification for this product.
Show details on NVD website

To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2024-39486",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2024-07-08T15:13:18.216624Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2024-07-08T15:13:34.330Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      },
      {
        "providerMetadata": {
          "dateUpdated": "2024-08-02T04:26:15.689Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/16682588ead4a593cf1aebb33b36df4d1e9e4ffa"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/0acce2a5c619ef1abdee783d7fea5eac78ce4844"
          },
          {
            "tags": [
              "x_transferred"
            ],
            "url": "https://git.kernel.org/stable/c/4f2a129b33a2054e62273edd5a051c34c08d96e9"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/drm_file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "16682588ead4a593cf1aebb33b36df4d1e9e4ffa",
              "status": "affected",
              "version": "031ddd28008971cce0b5626379b910d0a05fb4dd",
              "versionType": "git"
            },
            {
              "lessThan": "0acce2a5c619ef1abdee783d7fea5eac78ce4844",
              "status": "affected",
              "version": "1c7a387ffef894b1ab3942f0482dac7a6e0a909c",
              "versionType": "git"
            },
            {
              "lessThan": "4f2a129b33a2054e62273edd5a051c34c08d96e9",
              "status": "affected",
              "version": "1c7a387ffef894b1ab3942f0482dac7a6e0a909c",
              "versionType": "git"
            },
            {
              "lessThan": "6.6.37",
              "status": "affected",
              "version": "6.6.9",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/gpu/drm/drm_file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.7"
            },
            {
              "lessThan": "6.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.37",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.9.*",
              "status": "unaffected",
              "version": "6.9.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.10",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.37",
                  "versionStartIncluding": "6.6.9",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.9.8",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.10",
                  "versionStartIncluding": "6.7",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/drm_file: Fix pid refcounting race\n\n\u003cmaarten.lankhorst@linux.intel.com\u003e, Maxime Ripard\n\u003cmripard@kernel.org\u003e, Thomas Zimmermann \u003ctzimmermann@suse.de\u003e\n\nfilp-\u003epid is supposed to be a refcounted pointer; however, before this\npatch, drm_file_update_pid() only increments the refcount of a struct\npid after storing a pointer to it in filp-\u003epid and dropping the\ndev-\u003efilelist_mutex, making the following race possible:\n\nprocess A               process B\n=========               =========\n                        begin drm_file_update_pid\n                        mutex_lock(\u0026dev-\u003efilelist_mutex)\n                        rcu_replace_pointer(filp-\u003epid, \u003cpid B\u003e, 1)\n                        mutex_unlock(\u0026dev-\u003efilelist_mutex)\nbegin drm_file_update_pid\nmutex_lock(\u0026dev-\u003efilelist_mutex)\nrcu_replace_pointer(filp-\u003epid, \u003cpid A\u003e, 1)\nmutex_unlock(\u0026dev-\u003efilelist_mutex)\nget_pid(\u003cpid A\u003e)\nsynchronize_rcu()\nput_pid(\u003cpid B\u003e)   *** pid B reaches refcount 0 and is freed here ***\n                        get_pid(\u003cpid B\u003e)   *** UAF ***\n                        synchronize_rcu()\n                        put_pid(\u003cpid A\u003e)\n\nAs far as I know, this race can only occur with CONFIG_PREEMPT_RCU=y\nbecause it requires RCU to detect a quiescent state in code that is not\nexplicitly calling into the scheduler.\n\nThis race leads to use-after-free of a \"struct pid\".\nIt is probably somewhat hard to hit because process A has to pass\nthrough a synchronize_rcu() operation while process B is between\nmutex_unlock() and get_pid().\n\nFix it by ensuring that by the time a pointer to the current task\u0027s pid\nis stored in the file, an extra reference to the pid has been taken.\n\nThis fix also removes the condition for synchronize_rcu(); I think\nthat optimization is unnecessary complexity, since in that case we\nwould usually have bailed out on the lockless check above."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-23T15:50:17.182Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/16682588ead4a593cf1aebb33b36df4d1e9e4ffa"
        },
        {
          "url": "https://git.kernel.org/stable/c/0acce2a5c619ef1abdee783d7fea5eac78ce4844"
        },
        {
          "url": "https://git.kernel.org/stable/c/4f2a129b33a2054e62273edd5a051c34c08d96e9"
        }
      ],
      "title": "drm/drm_file: Fix pid refcounting race",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2024-39486",
    "datePublished": "2024-07-06T09:25:21.514Z",
    "dateReserved": "2024-06-25T14:23:23.747Z",
    "dateUpdated": "2026-05-23T15:50:17.182Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.