fkie_cve-2021-46939
Vulnerability from fkie_nvd
Published
2024-02-27 19:04
Modified
2025-04-22 16:15
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: tracing: Restructure trace_clock_global() to never block It was reported that a fix to the ring buffer recursion detection would cause a hung machine when performing suspend / resume testing. The following backtrace was extracted from debugging that case: Call Trace: trace_clock_global+0x91/0xa0 __rb_reserve_next+0x237/0x460 ring_buffer_lock_reserve+0x12a/0x3f0 trace_buffer_lock_reserve+0x10/0x50 __trace_graph_return+0x1f/0x80 trace_graph_return+0xb7/0xf0 ? trace_clock_global+0x91/0xa0 ftrace_return_to_handler+0x8b/0xf0 ? pv_hash+0xa0/0xa0 return_to_handler+0x15/0x30 ? ftrace_graph_caller+0xa0/0xa0 ? trace_clock_global+0x91/0xa0 ? __rb_reserve_next+0x237/0x460 ? ring_buffer_lock_reserve+0x12a/0x3f0 ? trace_event_buffer_lock_reserve+0x3c/0x120 ? trace_event_buffer_reserve+0x6b/0xc0 ? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0 ? dpm_run_callback+0x3b/0xc0 ? pm_ops_is_empty+0x50/0x50 ? platform_get_irq_byname_optional+0x90/0x90 ? trace_device_pm_callback_start+0x82/0xd0 ? dpm_run_callback+0x49/0xc0 With the following RIP: RIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200 Since the fix to the recursion detection would allow a single recursion to happen while tracing, this lead to the trace_clock_global() taking a spin lock and then trying to take it again: ring_buffer_lock_reserve() { trace_clock_global() { arch_spin_lock() { queued_spin_lock_slowpath() { /* lock taken */ (something else gets traced by function graph tracer) ring_buffer_lock_reserve() { trace_clock_global() { arch_spin_lock() { queued_spin_lock_slowpath() { /* DEAD LOCK! */ Tracing should *never* block, as it can lead to strange lockups like the above. Restructure the trace_clock_global() code to instead of simply taking a lock to update the recorded "prev_time" simply use it, as two events happening on two different CPUs that calls this at the same time, really doesn't matter which one goes first. Use a trylock to grab the lock for updating the prev_time, and if it fails, simply try again the next time. If it failed to be taken, that means something else is already updating it. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1fca00920327be96f3318224f502e4d5460f9545Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2a1bd74b8186d7938bf004f5603f25b84785f63ePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6e2418576228eeb12e7ba82edb8f9500623942ffPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8bPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/91ca6f6a91f679c8645d7f3307e03ce86ad518c4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a33614d52e97fc8077eb0b292189ca7d964cc534Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/aafe104aa9096827a429bc1358f8260ee565b7ccPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c64da3294a7d59a4bf6874c664c13be892f15f44Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d43d56dbf452ccecc1ec735cd4b6840118005d7cPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/1fca00920327be96f3318224f502e4d5460f9545Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/2a1bd74b8186d7938bf004f5603f25b84785f63ePatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/6e2418576228eeb12e7ba82edb8f9500623942ffPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/859b47a43f5a0e5b9a92b621dc6ceaad39fb5c8bPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/91ca6f6a91f679c8645d7f3307e03ce86ad518c4Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/a33614d52e97fc8077eb0b292189ca7d964cc534Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/aafe104aa9096827a429bc1358f8260ee565b7ccPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/c64da3294a7d59a4bf6874c664c13be892f15f44Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/d43d56dbf452ccecc1ec735cd4b6840118005d7cPatch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *


To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntracing: Restructure trace_clock_global() to never block\n\nIt was reported that a fix to the ring buffer recursion detection would\ncause a hung machine when performing suspend / resume testing. The\nfollowing backtrace was extracted from debugging that case:\n\nCall Trace:\n trace_clock_global+0x91/0xa0\n __rb_reserve_next+0x237/0x460\n ring_buffer_lock_reserve+0x12a/0x3f0\n trace_buffer_lock_reserve+0x10/0x50\n __trace_graph_return+0x1f/0x80\n trace_graph_return+0xb7/0xf0\n ? trace_clock_global+0x91/0xa0\n ftrace_return_to_handler+0x8b/0xf0\n ? pv_hash+0xa0/0xa0\n return_to_handler+0x15/0x30\n ? ftrace_graph_caller+0xa0/0xa0\n ? trace_clock_global+0x91/0xa0\n ? __rb_reserve_next+0x237/0x460\n ? ring_buffer_lock_reserve+0x12a/0x3f0\n ? trace_event_buffer_lock_reserve+0x3c/0x120\n ? trace_event_buffer_reserve+0x6b/0xc0\n ? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0\n ? dpm_run_callback+0x3b/0xc0\n ? pm_ops_is_empty+0x50/0x50\n ? platform_get_irq_byname_optional+0x90/0x90\n ? trace_device_pm_callback_start+0x82/0xd0\n ? dpm_run_callback+0x49/0xc0\n\nWith the following RIP:\n\nRIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200\n\nSince the fix to the recursion detection would allow a single recursion to\nhappen while tracing, this lead to the trace_clock_global() taking a spin\nlock and then trying to take it again:\n\nring_buffer_lock_reserve() {\n  trace_clock_global() {\n    arch_spin_lock() {\n      queued_spin_lock_slowpath() {\n        /* lock taken */\n        (something else gets traced by function graph tracer)\n          ring_buffer_lock_reserve() {\n            trace_clock_global() {\n              arch_spin_lock() {\n                queued_spin_lock_slowpath() {\n                /* DEAD LOCK! */\n\nTracing should *never* block, as it can lead to strange lockups like the\nabove.\n\nRestructure the trace_clock_global() code to instead of simply taking a\nlock to update the recorded \"prev_time\" simply use it, as two events\nhappening on two different CPUs that calls this at the same time, really\ndoesn\u0027t matter which one goes first. Use a trylock to grab the lock for\nupdating the prev_time, and if it fails, simply try again the next time.\nIf it failed to be taken, that means something else is already updating\nit.\n\n\nBugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761"
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: rastreo: reestructurar trace_clock_global() para no bloquear nunca. Se inform\u00f3 que una soluci\u00f3n a la detecci\u00f3n de recursividad del b\u00fafer circular provocar\u00eda que la m\u00e1quina se bloqueara al realizar pruebas de suspensi\u00f3n/reanudaci\u00f3n. El siguiente seguimiento se extrajo de la depuraci\u00f3n de ese caso: Call Trace: trace_clock_global+0x91/0xa0 __rb_reserve_next+0x237/0x460 ring_buffer_lock_reserve+0x12a/0x3f0 trace_buffer_lock_reserve+0x10/0x50 __trace_graph_return+0x1f/0x80 trace_graph_return+0xb7 /0xf0? trace_clock_global+0x91/0xa0 ftrace_return_to_handler+0x8b/0xf0 ? pv_hash+0xa0/0xa0 return_to_handler+0x15/0x30 ? ftrace_graph_caller+0xa0/0xa0? trace_clock_global+0x91/0xa0? __rb_reserve_next+0x237/0x460? ring_buffer_lock_reserve+0x12a/0x3f0? trace_event_buffer_lock_reserve+0x3c/0x120? trace_event_buffer_reserve+0x6b/0xc0? trace_event_raw_event_device_pm_callback_start+0x125/0x2d0? dpm_run_callback+0x3b/0xc0? pm_ops_is_empty+0x50/0x50? platform_get_irq_byname_opcional+0x90/0x90? trace_device_pm_callback_start+0x82/0xd0? dpm_run_callback+0x49/0xc0 Con el siguiente RIP: RIP: 0010:native_queued_spin_lock_slowpath+0x69/0x200 Dado que la soluci\u00f3n a la detecci\u00f3n de recursi\u00f3n permitir\u00eda que ocurriera una sola recursi\u00f3n durante el seguimiento, esto llev\u00f3 a trace_clock_global() a tomar un bloqueo de giro y luego intentarlo para tomarlo de nuevo: ring_buffer_lock_reserve() { trace_clock_global() { arch_spin_lock() { queued_spin_lock_slowpath() { /* bloqueo tomado */ (algo m\u00e1s es rastreado por la funci\u00f3n de seguimiento del gr\u00e1fico) ring_buffer_lock_reserve() { trace_clock_global() { arch_spin_lock() { queued_spin_lock_slowpath () { /* \u00a1BLOQUEO MUERTO! */ El rastreo *nunca* debe bloquearse, ya que puede provocar bloqueos extra\u00f1os como el anterior. Reestructura el c\u00f3digo trace_clock_global() para que, en lugar de simplemente tomar un bloqueo para actualizar el \"prev_time\" registrado, simplemente lo uses, ya que dos eventos suceden en dos CPU diferentes que llaman a esto al mismo tiempo, realmente no importa cu\u00e1l va primero. Utilice un trylock para obtener el bloqueo para actualizar prev_time y, si falla, simplemente int\u00e9ntelo de nuevo la pr\u00f3xima vez. Si no se pudo tomar, eso significa que algo m\u00e1s ya lo est\u00e1 actualizando. Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212761"
    }
  ],
  "id": "CVE-2021-46939",
  "lastModified": "2025-04-22T16:15:19.423",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "type": "Secondary"
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  "published": "2024-02-27T19:04:05.873",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-662"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        }
      ],
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "type": "Secondary"
    }
  ]
}


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