CVE-2022-50220 (GCVE-0-2022-50220)

Vulnerability from cvelistv5 – Published: 2025-06-18 11:03 – Updated: 2025-07-15 15:43
VLAI?
Title
usbnet: Fix linkwatch use-after-free on disconnect
Summary
In the Linux kernel, the following vulnerability has been resolved: usbnet: Fix linkwatch use-after-free on disconnect usbnet uses the work usbnet_deferred_kevent() to perform tasks which may sleep. On disconnect, completion of the work was originally awaited in ->ndo_stop(). But in 2003, that was moved to ->disconnect() by historic commit "[PATCH] USB: usbnet, prevent exotic rtnl deadlock": https://git.kernel.org/tglx/history/c/0f138bbfd83c The change was made because back then, the kernel's workqueue implementation did not allow waiting for a single work. One had to wait for completion of *all* work by calling flush_scheduled_work(), and that could deadlock when waiting for usbnet_deferred_kevent() with rtnl_mutex held in ->ndo_stop(). The commit solved one problem but created another: It causes a use-after-free in USB Ethernet drivers aqc111.c, asix_devices.c, ax88179_178a.c, ch9200.c and smsc75xx.c: * If the drivers receive a link change interrupt immediately before disconnect, they raise EVENT_LINK_RESET in their (non-sleepable) ->status() callback and schedule usbnet_deferred_kevent(). * usbnet_deferred_kevent() invokes the driver's ->link_reset() callback, which calls netif_carrier_{on,off}(). * That in turn schedules the work linkwatch_event(). Because usbnet_deferred_kevent() is awaited after unregister_netdev(), netif_carrier_{on,off}() may operate on an unregistered netdev and linkwatch_event() may run after free_netdev(), causing a use-after-free. In 2010, usbnet was changed to only wait for a single instance of usbnet_deferred_kevent() instead of *all* work by commit 23f333a2bfaf ("drivers/net: don't use flush_scheduled_work()"). Unfortunately the commit neglected to move the wait back to ->ndo_stop(). Rectify that omission at long last.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < d2d6b530d89b0a912148018027386aa049f0a309 (git)
Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < e2a521a7dcc463c5017b4426ca0804e151faeff7 (git)
Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < 7f77dcbc030c2faa6d8e8a594985eeb34018409e (git)
Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < 8b4588b8b00b299be16a35be67b331d8fdba03f3 (git)
Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < 135199a2edd459d2b123144efcd7f9bcd95128e4 (git)
Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < 635fd8953e4309b54ca6a81bed1d4a87668694f4 (git)
Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f (git)
Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < db3b738ae5f726204876f4303c49cfdf4311403f (git)
Affected: 23f333a2bfafba80339315b724808982a9de57d9 , < a69e617e533edddf3fa3123149900f36e0a6dc74 (git)
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    Linux Linux Affected: 2.6.38
Unaffected: 0 , < 2.6.38 (semver)
Unaffected: 4.9.326 , ≤ 4.9.* (semver)
Unaffected: 4.14.291 , ≤ 4.14.* (semver)
Unaffected: 4.19.256 , ≤ 4.19.* (semver)
Unaffected: 5.4.211 , ≤ 5.4.* (semver)
Unaffected: 5.10.137 , ≤ 5.10.* (semver)
Unaffected: 5.15.61 , ≤ 5.15.* (semver)
Unaffected: 5.18.18 , ≤ 5.18.* (semver)
Unaffected: 5.19.2 , ≤ 5.19.* (semver)
Unaffected: 6.0 , ≤ * (original_commit_for_fix)
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nusbnet: Fix linkwatch use-after-free on disconnect\n\nusbnet uses the work usbnet_deferred_kevent() to perform tasks which may\nsleep.  On disconnect, completion of the work was originally awaited in\n-\u003endo_stop().  But in 2003, that was moved to -\u003edisconnect() by historic\ncommit \"[PATCH] USB: usbnet, prevent exotic rtnl deadlock\":\n\n  https://git.kernel.org/tglx/history/c/0f138bbfd83c\n\nThe change was made because back then, the kernel\u0027s workqueue\nimplementation did not allow waiting for a single work.  One had to wait\nfor completion of *all* work by calling flush_scheduled_work(), and that\ncould deadlock when waiting for usbnet_deferred_kevent() with rtnl_mutex\nheld in -\u003endo_stop().\n\nThe commit solved one problem but created another:  It causes a\nuse-after-free in USB Ethernet drivers aqc111.c, asix_devices.c,\nax88179_178a.c, ch9200.c and smsc75xx.c:\n\n* If the drivers receive a link change interrupt immediately before\n  disconnect, they raise EVENT_LINK_RESET in their (non-sleepable)\n  -\u003estatus() callback and schedule usbnet_deferred_kevent().\n* usbnet_deferred_kevent() invokes the driver\u0027s -\u003elink_reset() callback,\n  which calls netif_carrier_{on,off}().\n* That in turn schedules the work linkwatch_event().\n\nBecause usbnet_deferred_kevent() is awaited after unregister_netdev(),\nnetif_carrier_{on,off}() may operate on an unregistered netdev and\nlinkwatch_event() may run after free_netdev(), causing a use-after-free.\n\nIn 2010, usbnet was changed to only wait for a single instance of\nusbnet_deferred_kevent() instead of *all* work by commit 23f333a2bfaf\n(\"drivers/net: don\u0027t use flush_scheduled_work()\").\n\nUnfortunately the commit neglected to move the wait back to\n-\u003endo_stop().  Rectify that omission at long last."
        }
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        "dateUpdated": "2025-07-15T15:43:48.595Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        {
          "url": "https://git.kernel.org/stable/c/d2d6b530d89b0a912148018027386aa049f0a309"
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        {
          "url": "https://git.kernel.org/stable/c/e2a521a7dcc463c5017b4426ca0804e151faeff7"
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          "url": "https://git.kernel.org/stable/c/7f77dcbc030c2faa6d8e8a594985eeb34018409e"
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        {
          "url": "https://git.kernel.org/stable/c/8b4588b8b00b299be16a35be67b331d8fdba03f3"
        },
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        },
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          "url": "https://git.kernel.org/stable/c/635fd8953e4309b54ca6a81bed1d4a87668694f4"
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        {
          "url": "https://git.kernel.org/stable/c/d49bb8cf9bfaa06aa527eb30f1a52a071da2e32f"
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        {
          "url": "https://git.kernel.org/stable/c/db3b738ae5f726204876f4303c49cfdf4311403f"
        },
        {
          "url": "https://git.kernel.org/stable/c/a69e617e533edddf3fa3123149900f36e0a6dc74"
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      "title": "usbnet: Fix linkwatch use-after-free on disconnect",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2022-50220",
    "datePublished": "2025-06-18T11:03:55.461Z",
    "dateReserved": "2025-06-18T10:57:27.430Z",
    "dateUpdated": "2025-07-15T15:43:48.595Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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