cve-2024-50275
Vulnerability from cvelistv5
Published
2024-11-19 01:30
Modified
2024-12-19 09:37
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: arm64/sve: Discard stale CPU state when handling SVE traps The logic for handling SVE traps manipulates saved FPSIMD/SVE state incorrectly, and a race with preemption can result in a task having TIF_SVE set and TIF_FOREIGN_FPSTATE clear even though the live CPU state is stale (e.g. with SVE traps enabled). This has been observed to result in warnings from do_sve_acc() where SVE traps are not expected while TIF_SVE is set: | if (test_and_set_thread_flag(TIF_SVE)) | WARN_ON(1); /* SVE access shouldn't have trapped */ Warnings of this form have been reported intermittently, e.g. https://lore.kernel.org/linux-arm-kernel/CA+G9fYtEGe_DhY2Ms7+L7NKsLYUomGsgqpdBj+QwDLeSg=JhGg@mail.gmail.com/ https://lore.kernel.org/linux-arm-kernel/000000000000511e9a060ce5a45c@google.com/ The race can occur when the SVE trap handler is preempted before and after manipulating the saved FPSIMD/SVE state, starting and ending on the same CPU, e.g. | void do_sve_acc(unsigned long esr, struct pt_regs *regs) | { | // Trap on CPU 0 with TIF_SVE clear, SVE traps enabled | // task->fpsimd_cpu is 0. | // per_cpu_ptr(&fpsimd_last_state, 0) is task. | | ... | | // Preempted; migrated from CPU 0 to CPU 1. | // TIF_FOREIGN_FPSTATE is set. | | get_cpu_fpsimd_context(); | | if (test_and_set_thread_flag(TIF_SVE)) | WARN_ON(1); /* SVE access shouldn't have trapped */ | | sve_init_regs() { | if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) { | ... | } else { | fpsimd_to_sve(current); | current->thread.fp_type = FP_STATE_SVE; | } | } | | put_cpu_fpsimd_context(); | | // Preempted; migrated from CPU 1 to CPU 0. | // task->fpsimd_cpu is still 0 | // If per_cpu_ptr(&fpsimd_last_state, 0) is still task then: | // - Stale HW state is reused (with SVE traps enabled) | // - TIF_FOREIGN_FPSTATE is cleared | // - A return to userspace skips HW state restore | } Fix the case where the state is not live and TIF_FOREIGN_FPSTATE is set by calling fpsimd_flush_task_state() to detach from the saved CPU state. This ensures that a subsequent context switch will not reuse the stale CPU state, and will instead set TIF_FOREIGN_FPSTATE, forcing the new state to be reloaded from memory prior to a return to userspace.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/51d11ea0250d6ee461987403bbfd4b2abb5613a7Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/51d3d80a6dc314982a9a0aeb0961085922a1aa15
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/751ecf6afd6568adc98f2a6052315552c0483d18Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/de529504b3274d57caf8f66800b714b0d3ee235a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fa9ce027b3ce37a2bb173bf2553b5caa438fd8c9Patch
Impacted products
Vendor Product Version
Linux Linux Version: cccb78ce89c45a4414db712be4986edfb92434bd
Version: cccb78ce89c45a4414db712be4986edfb92434bd
Version: cccb78ce89c45a4414db712be4986edfb92434bd
Version: cccb78ce89c45a4414db712be4986edfb92434bd
Version: cccb78ce89c45a4414db712be4986edfb92434bd
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   Linux Linux Version: 5.13
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kernel/fpsimd.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "51d3d80a6dc314982a9a0aeb0961085922a1aa15",
              "status": "affected",
              "version": "cccb78ce89c45a4414db712be4986edfb92434bd",
              "versionType": "git"
            },
            {
              "lessThan": "de529504b3274d57caf8f66800b714b0d3ee235a",
              "status": "affected",
              "version": "cccb78ce89c45a4414db712be4986edfb92434bd",
              "versionType": "git"
            },
            {
              "lessThan": "51d11ea0250d6ee461987403bbfd4b2abb5613a7",
              "status": "affected",
              "version": "cccb78ce89c45a4414db712be4986edfb92434bd",
              "versionType": "git"
            },
            {
              "lessThan": "fa9ce027b3ce37a2bb173bf2553b5caa438fd8c9",
              "status": "affected",
              "version": "cccb78ce89c45a4414db712be4986edfb92434bd",
              "versionType": "git"
            },
            {
              "lessThan": "751ecf6afd6568adc98f2a6052315552c0483d18",
              "status": "affected",
              "version": "cccb78ce89c45a4414db712be4986edfb92434bd",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/kernel/fpsimd.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.13"
            },
            {
              "lessThan": "5.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.174",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.120",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.61",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.11.*",
              "status": "unaffected",
              "version": "6.11.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.12",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64/sve: Discard stale CPU state when handling SVE traps\n\nThe logic for handling SVE traps manipulates saved FPSIMD/SVE state\nincorrectly, and a race with preemption can result in a task having\nTIF_SVE set and TIF_FOREIGN_FPSTATE clear even though the live CPU state\nis stale (e.g. with SVE traps enabled). This has been observed to result\nin warnings from do_sve_acc() where SVE traps are not expected while\nTIF_SVE is set:\n\n|         if (test_and_set_thread_flag(TIF_SVE))\n|                 WARN_ON(1); /* SVE access shouldn\u0027t have trapped */\n\nWarnings of this form have been reported intermittently, e.g.\n\n  https://lore.kernel.org/linux-arm-kernel/CA+G9fYtEGe_DhY2Ms7+L7NKsLYUomGsgqpdBj+QwDLeSg=JhGg@mail.gmail.com/\n  https://lore.kernel.org/linux-arm-kernel/000000000000511e9a060ce5a45c@google.com/\n\nThe race can occur when the SVE trap handler is preempted before and\nafter manipulating the saved FPSIMD/SVE state, starting and ending on\nthe same CPU, e.g.\n\n| void do_sve_acc(unsigned long esr, struct pt_regs *regs)\n| {\n|         // Trap on CPU 0 with TIF_SVE clear, SVE traps enabled\n|         // task-\u003efpsimd_cpu is 0.\n|         // per_cpu_ptr(\u0026fpsimd_last_state, 0) is task.\n|\n|         ...\n|\n|         // Preempted; migrated from CPU 0 to CPU 1.\n|         // TIF_FOREIGN_FPSTATE is set.\n|\n|         get_cpu_fpsimd_context();\n|\n|         if (test_and_set_thread_flag(TIF_SVE))\n|                 WARN_ON(1); /* SVE access shouldn\u0027t have trapped */\n|\n|         sve_init_regs() {\n|                 if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {\n|                         ...\n|                 } else {\n|                         fpsimd_to_sve(current);\n|                         current-\u003ethread.fp_type = FP_STATE_SVE;\n|                 }\n|         }\n|\n|         put_cpu_fpsimd_context();\n|\n|         // Preempted; migrated from CPU 1 to CPU 0.\n|         // task-\u003efpsimd_cpu is still 0\n|         // If per_cpu_ptr(\u0026fpsimd_last_state, 0) is still task then:\n|         // - Stale HW state is reused (with SVE traps enabled)\n|         // - TIF_FOREIGN_FPSTATE is cleared\n|         // - A return to userspace skips HW state restore\n| }\n\nFix the case where the state is not live and TIF_FOREIGN_FPSTATE is set\nby calling fpsimd_flush_task_state() to detach from the saved CPU\nstate. This ensures that a subsequent context switch will not reuse the\nstale CPU state, and will instead set TIF_FOREIGN_FPSTATE, forcing the\nnew state to be reloaded from memory prior to a return to userspace."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2024-12-19T09:37:06.056Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/51d3d80a6dc314982a9a0aeb0961085922a1aa15"
        },
        {
          "url": "https://git.kernel.org/stable/c/de529504b3274d57caf8f66800b714b0d3ee235a"
        },
        {
          "url": "https://git.kernel.org/stable/c/51d11ea0250d6ee461987403bbfd4b2abb5613a7"
        },
        {
          "url": "https://git.kernel.org/stable/c/fa9ce027b3ce37a2bb173bf2553b5caa438fd8c9"
        },
        {
          "url": "https://git.kernel.org/stable/c/751ecf6afd6568adc98f2a6052315552c0483d18"
        }
      ],
      "title": "arm64/sve: Discard stale CPU state when handling SVE traps",
      "x_generator": {
        "engine": "bippy-5f407fcff5a0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2024-50275",
    "datePublished": "2024-11-19T01:30:15.293Z",
    "dateReserved": "2024-10-21T19:36:19.983Z",
    "dateUpdated": "2024-12-19T09:37:06.056Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2024-50275\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2024-11-19T02:16:29.760\",\"lastModified\":\"2024-12-14T21:15:34.270\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\narm64/sve: Discard stale CPU state when handling SVE traps\\n\\nThe logic for handling SVE traps manipulates saved FPSIMD/SVE state\\nincorrectly, and a race with preemption can result in a task having\\nTIF_SVE set and TIF_FOREIGN_FPSTATE clear even though the live CPU state\\nis stale (e.g. with SVE traps enabled). This has been observed to result\\nin warnings from do_sve_acc() where SVE traps are not expected while\\nTIF_SVE is set:\\n\\n|         if (test_and_set_thread_flag(TIF_SVE))\\n|                 WARN_ON(1); /* SVE access shouldn\u0027t have trapped */\\n\\nWarnings of this form have been reported intermittently, e.g.\\n\\n  https://lore.kernel.org/linux-arm-kernel/CA+G9fYtEGe_DhY2Ms7+L7NKsLYUomGsgqpdBj+QwDLeSg=JhGg@mail.gmail.com/\\n  https://lore.kernel.org/linux-arm-kernel/000000000000511e9a060ce5a45c@google.com/\\n\\nThe race can occur when the SVE trap handler is preempted before and\\nafter manipulating the saved FPSIMD/SVE state, starting and ending on\\nthe same CPU, e.g.\\n\\n| void do_sve_acc(unsigned long esr, struct pt_regs *regs)\\n| {\\n|         // Trap on CPU 0 with TIF_SVE clear, SVE traps enabled\\n|         // task-\u003efpsimd_cpu is 0.\\n|         // per_cpu_ptr(\u0026fpsimd_last_state, 0) is task.\\n|\\n|         ...\\n|\\n|         // Preempted; migrated from CPU 0 to CPU 1.\\n|         // TIF_FOREIGN_FPSTATE is set.\\n|\\n|         get_cpu_fpsimd_context();\\n|\\n|         if (test_and_set_thread_flag(TIF_SVE))\\n|                 WARN_ON(1); /* SVE access shouldn\u0027t have trapped */\\n|\\n|         sve_init_regs() {\\n|                 if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) {\\n|                         ...\\n|                 } else {\\n|                         fpsimd_to_sve(current);\\n|                         current-\u003ethread.fp_type = FP_STATE_SVE;\\n|                 }\\n|         }\\n|\\n|         put_cpu_fpsimd_context();\\n|\\n|         // Preempted; migrated from CPU 1 to CPU 0.\\n|         // task-\u003efpsimd_cpu is still 0\\n|         // If per_cpu_ptr(\u0026fpsimd_last_state, 0) is still task then:\\n|         // - Stale HW state is reused (with SVE traps enabled)\\n|         // - TIF_FOREIGN_FPSTATE is cleared\\n|         // - A return to userspace skips HW state restore\\n| }\\n\\nFix the case where the state is not live and TIF_FOREIGN_FPSTATE is set\\nby calling fpsimd_flush_task_state() to detach from the saved CPU\\nstate. This ensures that a subsequent context switch will not reuse the\\nstale CPU state, and will instead set TIF_FOREIGN_FPSTATE, forcing the\\nnew state to be reloaded from memory prior to a return to userspace.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: arm64/sve: descartar estado de CPU obsoleto al manejar trampas SVE La l\u00f3gica para manejar trampas SVE manipula incorrectamente el estado FPSIMD/SVE guardado, y una ejecuci\u00f3n con preempci\u00f3n puede resultar en una tarea que tenga TIF_SVE establecido y TIF_FOREIGN_FPSTATE borrado incluso aunque el estado de CPU en vivo est\u00e9 obsoleto (por ejemplo, con trampas SVE habilitadas). Se ha observado que esto da como resultado advertencias de do_sve_acc() donde no se esperan trampas SVE mientras TIF_SVE est\u00e1 establecido: | if (test_and_set_thread_flag(TIF_SVE)) | WARN_ON(1); /* El acceso a SVE no deber\u00eda haber generado una trampa */ Se han informado advertencias de este formato de forma intermitente, por ejemplo, https://lore.kernel.org/linux-arm-kernel/CA+G9fYtEGe_DhY2Ms7+L7NKsLYUomGsgqpdBj+QwDLeSg=JhGg@mail.gmail.com/ https://lore.kernel.org/linux-arm-kernel/000000000000511e9a060ce5a45c@google.com/ La ejecuci\u00f3n puede ocurrir cuando el controlador de trampa SVE se interrumpe antes y despu\u00e9s de manipular el estado FPSIMD/SVE guardado, comenzando y terminando en la misma CPU, por ejemplo, | void do_sve_acc(unsigned long esr, struct pt_regs *regs) | { | // Trampa en CPU 0 con TIF_SVE limpio, trampas SVE habilitadas | // task-\u0026gt;fpsimd_cpu es 0. | // per_cpu_ptr(\u0026amp;fpsimd_last_state, 0) es la tarea. | | ... | | // Preempleado; migrado de la CPU 0 a la CPU 1. | // TIF_FOREIGN_FPSTATE est\u00e1 establecido. | | get_cpu_fpsimd_context(); | | if (test_and_set_thread_flag(TIF_SVE)) | WARN_ON(1); /* El acceso a SVE no deber\u00eda haber quedado atrapado */ | | sve_init_regs() { | if (!test_thread_flag(TIF_FOREIGN_FPSTATE)) { | ... | } else { | fpsimd_to_sve(current); | current-\u0026gt;thread.fp_type = FP_STATE_SVE; | } | } | | put_cpu_fpsimd_context(); | | // Preempleado; migrado de CPU 1 a CPU 0. | // task-\u0026gt;fpsimd_cpu sigue siendo 0 | // Si per_cpu_ptr(\u0026amp;fpsimd_last_state, 0) sigue siendo tarea entonces: | // - Se reutiliza el estado de HW obsoleto (con trampas SVE habilitadas) | // - Se borra TIF_FOREIGN_FPSTATE | // - Un retorno al espacio de usuario omite la restauraci\u00f3n del estado de HW | } Corrija el caso donde el estado no est\u00e1 activo y TIF_FOREIGN_FPSTATE se establece llamando a fpsimd_flush_task_state() para separarse del estado de CPU guardado. Esto garantiza que un cambio de contexto posterior no reutilizar\u00e1 el estado de CPU obsoleto y, en su lugar, establecer\u00e1 TIF_FOREIGN_FPSTATE, lo que obligar\u00e1 a que el nuevo estado se vuelva a cargar desde la memoria antes de un retorno al espacio de usuario.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.0,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.0,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"NVD-CWE-noinfo\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.13\",\"versionEndExcluding\":\"6.6.61\",\"matchCriteriaId\":\"4713F9C0-902B-42E7-8BC3-EA25AE3D4238\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.11.8\",\"matchCriteriaId\":\"0BD000F7-3DAD-4DD3-8906-98EA1EC67E95\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.12:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"7F361E1D-580F-4A2D-A509-7615F73167A1\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.12:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"925478D0-3E3D-4E6F-ACD5-09F28D5DF82C\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.12:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"3C95E234-D335-4B6C-96BF-E2CEBD8654ED\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.12:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"E0F717D8-3014-4F84-8086-0124B2111379\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.12:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"24DBE6C7-2AAE-4818-AED2-E131F153D2FA\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.12:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"24B88717-53F5-42AA-9B72-14C707639E3F\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/51d11ea0250d6ee461987403bbfd4b2abb5613a7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/51d3d80a6dc314982a9a0aeb0961085922a1aa15\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/751ecf6afd6568adc98f2a6052315552c0483d18\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/de529504b3274d57caf8f66800b714b0d3ee235a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/fa9ce027b3ce37a2bb173bf2553b5caa438fd8c9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
  }
}


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