{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98745", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.367Z", "datePublished": "2026-10-18T15:47:30.967Z", "dateUpdated": "2026-10-21T12:56:21.116Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-21T12:56:21.116Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64/fpsimd: signal: Forbid non-streaming SVE payload on SME-only systems\n\nWhen system_supports_sme() is true but system_supports_sve() is false,\nrestoring a specifically crafted SVE signal context can result in the\ntask erroneously having non-streaming SVE state. Subsequent attempts to\nmanipulate the task's FPSIMD/SVE/SME state can result in a variety of\nproblems, including fatal EL1 UNDEFs.\n\nIn such configurations, the kernel always creates an SVE signal context\nwhen delivering a signal, and this can only be in one of two states:\n\n(1) SVE_SIG_FLAG_SM is set, and an SVE payload is present containing\n streaming mode SVE state. The recorded VL is the task's live\n streaming VL.\n\n(2) SVE_SIG_FLAG_SM is clear, and an SVE payload is not present. The\n FPSIMD context contains the non-streaming mode FPSIMD state. The\n recorded VL is 0.\n\nCurrently restore_sve_fpsimd_context() correctly rejects cases where\nSVE_SIG_FLAG_SM is set and an SVE payload is not present, but fails to\nreject cases where SVE_SIG_FLAG_SM is clear and an SVE payload is\npresent. Consequently, restore_sve_fpsimd_context() can place the task\nin a state where it has non-streaming SVE state even when this is not\nsupported by HW.\n\nFor example, this can cause a later EL1 UNDEF when the kernel attempts to\nrestore the task's ZCR_EL1 value:\n\n| # ./sme-sigcontext-to-sve\n| Internal error: Oops - Undefined instruction: 0000000002000000 [#1] SMP\n| Modules linked in:\n| CPU: 0 UID: 0 PID: 131 Comm: sme-sigcontext- Not tainted 7.3.0-rc1 #1 PREEMPT\n| Hardware name: linux,dummy-virt (DT)\n| pstate: 61402009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)\n| pc : fpsimd_restore_current_state+0x258/0x458\n| lr : exit_to_user_mode_loop+0xb8/0x188\n| sp : ffff80008056be40\n| x29: ffff80008056be40 x28: fff00000c1670000 x27: 0000000000000000\n| x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000\n| x23: ffff80008056bec0 x22: 0000000000000008 x21: 0000000000000040\n| x20: 0000000000000081 x19: 0000000008800010 x18: 0000000000000000\n| x17: 0000fffffd412570 x16: 0000000000001000 x15: 0000fffffd4123b0\n| x14: 0000fffffd412780 x13: 0000fffffd412be8 x12: 0000000047435300\n| x11: 0000fffffd412570 x10: 0000000000000000 x9 : 0000000045585401\n| x8 : fff00000c18a6c44 x7 : 0000000000000000 x6 : 0000000000000002\n| x5 : 0000000000000002 x4 : ffff800080568000 x3 : 0000000000000001\n| x2 : 0000000008800010 x1 : fff00000c1670000 x0 : 0000000008800000\n| Call trace:\n| fpsimd_restore_current_state+0x258/0x458 (P)\n| exit_to_user_mode_loop+0xb8/0x188\n| el0_svc+0x1cc/0x1d0\n| el0t_64_sync_handler+0xa0/0xe4\n| el0t_64_sync+0x198/0x19c\n| Code: d5384101 f9400020 53175c03 36b80de0 (d5381202)\n| ---[ end trace 0000000000000000 ]---\n| Kernel panic - not syncing: Oops - Undefined instruction: Fatal exception in interrupt\n| Kernel Offset: 0x291fb1000000 from 0xffff800080000000\n| PHYS_OFFSET: 0x40000000\n| CPU features: 0x0,00000000,0052802f,ffb88f43,3afcf73f\n| Memory Limit: none\n\nRework restore_sve_fpsimd_context() to reject cases where\nSVE_SIG_FLAG_SM is clear and an SVE payload is not present. As\nparse_user_sigframe() rejects SVE signal frames when neither SVE nor SME\nare supported, it isn't necessary for restore_sve_fpsimd_context() to\nhandle the case where neither are supported." } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/kernel/signal.c" ], "versions": [ { "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033", "lessThan": "052acee9880114879b5c221fc8dad69b786d0938", "status": "affected", "versionType": "git" }, { "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033", "lessThan": "f2338929c7663859c0c74dd6fef2c0245066f845", "status": "affected", "versionType": "git" }, { "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033", "lessThan": "2bce6f006cfe0b60e8249fd8d51396d99355cba3", "status": "affected", "versionType": "git" }, { "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033", "lessThan": "88c1c611552b24658eb61244086691c02be2013b", "status": "affected", "versionType": "git" }, { "version": "7dde62f0687c8856b6c0660066c7ee83a6a6f033", "lessThan": "e060d9069b49fe55f38057dfe592068014652671", "status": "affected", "versionType": "git" }, { "version": "05458ee3ff82b31a4564836a84ef20d6c233dfc7", "status": "affected", "versionType": "git" }, { "version": "6.1.7", "lessThan": "6.2", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/arm64/kernel/signal.c" ], "versions": [ { "version": "6.2", "status": "affected" }, { "version": "0", "lessThan": "6.2", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.160", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.113", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.56", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.10", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "6.2", "versionEndExcluding": "6.6.160" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.12.113" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.18.56" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "7.2.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "7.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.7" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/052acee9880114879b5c221fc8dad69b786d0938" }, { "url": "https://git.kernel.org/stable/c/f2338929c7663859c0c74dd6fef2c0245066f845" }, { "url": "https://git.kernel.org/stable/c/2bce6f006cfe0b60e8249fd8d51396d99355cba3" }, { "url": "https://git.kernel.org/stable/c/88c1c611552b24658eb61244086691c02be2013b" }, { "url": "https://git.kernel.org/stable/c/e060d9069b49fe55f38057dfe592068014652671" } ], "title": "arm64/fpsimd: signal: Forbid non-streaming SVE payload on SME-only systems", "x_generator": { "engine": "bippy-1.2.0" } } } }