{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-50275", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-10-21T19:36:19.983Z", "datePublished": "2024-11-19T01:30:15.293Z", "dateUpdated": "2026-08-05T11:42:58.345Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:42:58.345Z" }, "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't 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->fpsimd_cpu is 0.\n| // per_cpu_ptr(&fpsimd_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't 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->thread.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->fpsimd_cpu is still 0\n| // If per_cpu_ptr(&fpsimd_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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H", "baseScore": 7.3, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is the EL0 SVE access trap handler, reached only by a local process on the machine executing an SVE instruction. No network or remote input is involved.\nAC:L - The attacker controls both halves of the race — both windows around get/put_cpu_fpsimd_context() are fully preemptible, and the attacker can force preemption and CPU0→CPU1→CPU0 migration by oversubscribing a restricted affinity mask, while re-arming the SVE trap indefinitely (any syscall saves state as FPSIMD, clearing TIF_SVE and re-enabling the trap).\nPR:L - Only the ability to run unprivileged code is needed; el0_sve_acc()/do_sve_acc() perform no capability, namespace, or credential check of any kind.\nUI:N - The attacking process triggers the trap and the race entirely on its own; no action by any other user is required.\nS:U - The impact stays within the kernel/OS security authority — corrupted FP/SVE state tracking and kernel warnings on the same host, with no VM, IOMMU, or hypervisor boundary crossed.\nC:H - Skipping sve_flush_live() leaves SVE predicate registers P0-P15 and FFR from a previously running task's SVE context in the register file while the kernel treats them as the current task's live SVE state, so they are saved into thread.sve_state and copied to userspace by preserve_sve_context() (or read via ptrace NT_ARM_SVE) — a cross-process disclosure of up to 17 × VL/8 bytes, ~4 KB on max-VL hardware.\nI:L - Foreign SVE predicate/FFR contents are injected into the task's architectural state and the correctly converted in-memory state is silently discarded, but the WARN_ON(sve_get_vl() != vl) guard in fpsimd_save_user_state() blocks the mismatched-VL out-of-bounds save, so there is no arbitrary-write or control-flow primitive.\nA:H - The stale state reliably produces the WARN_ON(1) splat in do_sve_acc() — a kernel panic on the many panic_on_warn deployments (CI, hardened, cloud, Android) — and the VL-mismatch path additionally force-SIGKILLs the task; an unprivileged user can trigger this in a tight loop." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/kernel/fpsimd.c" ], "versions": [ { "version": "cccb78ce89c45a4414db712be4986edfb92434bd", "lessThan": "51d3d80a6dc314982a9a0aeb0961085922a1aa15", "status": "affected", "versionType": "git" }, { "version": "cccb78ce89c45a4414db712be4986edfb92434bd", "lessThan": "de529504b3274d57caf8f66800b714b0d3ee235a", "status": "affected", "versionType": "git" }, { "version": "cccb78ce89c45a4414db712be4986edfb92434bd", "lessThan": "51d11ea0250d6ee461987403bbfd4b2abb5613a7", "status": "affected", "versionType": "git" }, { "version": "cccb78ce89c45a4414db712be4986edfb92434bd", "lessThan": "fa9ce027b3ce37a2bb173bf2553b5caa438fd8c9", "status": "affected", "versionType": "git" }, { "version": "cccb78ce89c45a4414db712be4986edfb92434bd", "lessThan": "751ecf6afd6568adc98f2a6052315552c0483d18", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/kernel/fpsimd.c" ], "versions": [ { "version": "5.13", "status": "affected" }, { "version": "0", "lessThan": "5.13", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.174", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.120", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.61", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.11.8", "lessThanOrEqual": "6.11.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "5.15.174" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.1.120" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.6.61" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.11.8" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.13", "versionEndExcluding": "6.12" } ] } ] } ], "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-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T20:44:51.635Z" } } ] } }