{"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"}}]}}