{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2023-53713","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-10-22T13:21:37.347Z","datePublished":"2025-10-22T13:23:47.720Z","dateUpdated":"2026-08-05T09:15:40.426Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T09:15:40.426Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\narm64: sme: Use STR P to clear FFR context field in streaming SVE mode\n\nThe FFR is a predicate register which can vary between 16 and 256 bits\nin size depending upon the configured vector length. When saving the\nSVE state in streaming SVE mode, the FFR register is inaccessible and\nso commit 9f5848665788 (\"arm64/sve: Make access to FFR optional\") simply\nclears the FFR field of the in-memory context structure. Unfortunately,\nit achieves this using an unconditional 8-byte store and so if the SME\nvector length is anything other than 64 bytes in size we will either\nfail to clear the entire field or, worse, we will corrupt memory\nimmediately following the structure. This has led to intermittent kfence\nsplats in CI [1] and can trigger kmalloc Redzone corruption messages\nwhen running the 'fp-stress' kselftest:\n\n | =============================================================================\n | BUG kmalloc-1k (Not tainted): kmalloc Redzone overwritten\n | -----------------------------------------------------------------------------\n |\n | 0xffff000809bf1e22-0xffff000809bf1e27 @offset=7714. First byte 0x0 instead of 0xcc\n | Allocated in do_sme_acc+0x9c/0x220 age=2613 cpu=1 pid=531\n |  __kmalloc+0x8c/0xcc\n |  do_sme_acc+0x9c/0x220\n |  ...\n\nReplace the 8-byte store with a store of a predicate register which has\nbeen zero-initialised with PFALSE, ensuring that the entire field is\ncleared in memory.\n\n[1] https://lore.kernel.org/r/CA+G9fYtU7HsV0R0dp4XEH5xXHSJFw8KyDf5VQrLLfMxWfxQkag@mail.gmail.com"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - Triggering requires executing code on the target: an unprivileged `prctl(PR_SME_SET_VL)` followed by an EL0 `SMSTART SM` instruction and a context switch. There is no remote or adjacent-network path to `fpsimd_save()`.\nAC:L - The attacker fully controls every triggering condition — the streaming vector length via prctl, entry into streaming SVE mode, and the context switch that invokes `sve_save_state()` — so the out-of-bounds store fires deterministically on every save, and the operation can be repeated in a tight loop to groom the slab.\nPR:L - `sme_set_current_vl()` and the SME access trap handler `do_sme_acc()` perform no capability or credential checks whatsoever; any ordinary unprivileged user process on an SME-capable system reaches the vulnerable store.\nUI:N - The attacking process triggers the save path entirely on its own via prctl plus an instruction; no victim action, file open, or mount is involved.\nS:U - The corruption occurs in the kernel's own slab allocation for the calling task's FP state, staying within the kernel's security authority — no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The out-of-bounds write past the end of a kmalloc'd object is memory corruption of attacker-selectable allocation size, leverageable via heap grooming to zero length/pointer/refcount fields of a neighbouring object and thereby obtain kernel memory disclosure; additionally, for streaming vector lengths above 512 bits the FFR field is only partially cleared, and that stale in-kernel state is copied out to userspace through the SVE signal frame and the `NT_ARM_SSVE` ptrace regset.\nI:H - This is a heap out-of-bounds write — up to six zero bytes written beyond the end of a `kzalloc()`ed `task->thread.sve_state` buffer, confirmed in practice by kmalloc redzone-overwrite reports. Zeroing the leading bytes of an adjacent slab object (refcounts, pointers, flags) is a well-established primitive for corrupting kernel state and escalating privileges.\nA:H - The OOB store corrupts memory immediately following the slab object and produces kernel oopses in practice — the fix was prompted by intermittent KFENCE guard-page splats in CI, where the write lands on a guard page and faults at EL1, and SLUB redzone corruption detection can panic a hardened kernel."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/arm64/include/asm/fpsimdmacros.h"],"versions":[{"version":"9f5848665788a0f07bc175cb2cdd06d367b7556e","lessThan":"97669214944e80d3756657c21c4f286f3da6a423","status":"affected","versionType":"git"},{"version":"9f5848665788a0f07bc175cb2cdd06d367b7556e","lessThan":"8769a62faacbbb6cac5e35d9047ce445183d4e9f","status":"affected","versionType":"git"},{"version":"9f5848665788a0f07bc175cb2cdd06d367b7556e","lessThan":"1403a899153a12d93fd510e463fd6d0eafba4336","status":"affected","versionType":"git"},{"version":"9f5848665788a0f07bc175cb2cdd06d367b7556e","lessThan":"893b24181b4c4bf1fa2841b1ed192e5413a97cb1","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/include/asm/fpsimdmacros.h"],"versions":[{"version":"5.16","status":"affected"},{"version":"0","lessThan":"5.16","status":"unaffected","versionType":"semver"},{"version":"6.1.39","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.3.13","lessThanOrEqual":"6.3.*","status":"unaffected","versionType":"semver"},{"version":"6.4.4","lessThanOrEqual":"6.4.*","status":"unaffected","versionType":"semver"},{"version":"6.5","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":"5.16","versionEndExcluding":"6.1.39"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.3.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.4.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.16","versionEndExcluding":"6.5"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/97669214944e80d3756657c21c4f286f3da6a423"},{"url":"https://git.kernel.org/stable/c/8769a62faacbbb6cac5e35d9047ce445183d4e9f"},{"url":"https://git.kernel.org/stable/c/1403a899153a12d93fd510e463fd6d0eafba4336"},{"url":"https://git.kernel.org/stable/c/893b24181b4c4bf1fa2841b1ed192e5413a97cb1"}],"title":"arm64: sme: Use STR P to clear FFR context field in streaming SVE mode","x_generator":{"engine":"bippy-1.2.0"}}}}