CVE-2026-98745
- Source
- https://cve.org/CVERecord?id=CVE-2026-98745
- Import Source
- https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98745.json
- JSON Data
- https://api.osv.dev/v1/vulns/CVE-2026-98745
- Downstream
- Published
- 2026-10-18T15:47:30Z
- Modified
- 2026-10-20T02:30:53Z
- Summary
- arm64/fpsimd: signal: Forbid non-streaming SVE payload on SME-only systems
- Details
-
In the Linux kernel, the following vulnerability has been resolved:
arm64/fpsimd: signal: Forbid non-streaming SVE payload on SME-only systems
When system_supports_sme() is true but system_supports_sve() is false, restoring a specifically crafted SVE signal context can result in the task erroneously having non-streaming SVE state. Subsequent attempts to manipulate the task's FPSIMD/SVE/SME state can result in a variety of problems, including fatal EL1 UNDEFs.
In such configurations, the kernel always creates an SVE signal context when delivering a signal, and this can only be in one of two states:
(1) SVE_SIG_FLAG_SM is set, and an SVE payload is present containing streaming mode SVE state. The recorded VL is the task's live streaming VL.
(2) SVE_SIG_FLAG_SM is clear, and an SVE payload is not present. The FPSIMD context contains the non-streaming mode FPSIMD state. The recorded VL is 0.
Currently restore_sve_fpsimd_context() correctly rejects cases where SVE_SIG_FLAG_SM is set and an SVE payload is not present, but fails to reject cases where SVE_SIG_FLAG_SM is clear and an SVE payload is present. Consequently, restore_sve_fpsimd_context() can place the task in a state where it has non-streaming SVE state even when this is not supported by HW.
For example, this can cause a later EL1 UNDEF when the kernel attempts to restore the task's ZCR_EL1 value:
| # ./sme-sigcontext-to-sve | Internal error: Oops - Undefined instruction: 0000000002000000 [#1] SMP | Modules linked in: | CPU: 0 UID: 0 PID: 131 Comm: sme-sigcontext- Not tainted 7.3.0-rc1 #1 PREEMPT | Hardware name: linux,dummy-virt (DT) | pstate: 61402009 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--) | pc : fpsimd_restore_current_state+0x258/0x458 | lr : exit_to_user_mode_loop+0xb8/0x188 | sp : ffff80008056be40 | x29: ffff80008056be40 x28: fff00000c1670000 x27: 0000000000000000 | x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 | x23: ffff80008056bec0 x22: 0000000000000008 x21: 0000000000000040 | x20: 0000000000000081 x19: 0000000008800010 x18: 0000000000000000 | x17: 0000fffffd412570 x16: 0000000000001000 x15: 0000fffffd4123b0 | x14: 0000fffffd412780 x13: 0000fffffd412be8 x12: 0000000047435300 | x11: 0000fffffd412570 x10: 0000000000000000 x9 : 0000000045585401 | x8 : fff00000c18a6c44 x7 : 0000000000000000 x6 : 0000000000000002 | x5 : 0000000000000002 x4 : ffff800080568000 x3 : 0000000000000001 | x2 : 0000000008800010 x1 : fff00000c1670000 x0 : 0000000008800000 | Call trace: | fpsimd_restore_current_state+0x258/0x458 (P) | exit_to_user_mode_loop+0xb8/0x188 | el0_svc+0x1cc/0x1d0 | el0t_64_sync_handler+0xa0/0xe4 | el0t_64_sync+0x198/0x19c | Code: d5384101 f9400020 53175c03 36b80de0 (d5381202) | ---[ end trace 0000000000000000 ]--- | Kernel panic - not syncing: Oops - Undefined instruction: Fatal exception in interrupt | Kernel Offset: 0x291fb1000000 from 0xffff800080000000 | PHYS_OFFSET: 0x40000000 | CPU features: 0x0,00000000,0052802f,ffb88f43,3afcf73f | Memory Limit: none
Rework restore_sve_fpsimd_context() to reject cases where SVE_SIG_FLAG_SM is clear and an SVE payload is not present. As parse_user_sigframe() rejects SVE signal frames when neither SVE nor SME are supported, it isn't necessary for restore_sve_fpsimd_context() to handle the case where neither are supported.
- Database specific
{ "cna_assigner": "Linux", "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98745.json" }- References
-
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- https://git.kernel.org/stable/c/2bce6f006cfe0b60e8249fd8d51396d99355cba3
- https://git.kernel.org/stable/c/88c1c611552b24658eb61244086691c02be2013b
- https://git.kernel.org/stable/c/e060d9069b49fe55f38057dfe592068014652671
- https://git.kernel.org/stable/c/f2338929c7663859c0c74dd6fef2c0245066f845
- https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98745.json
- https://nvd.nist.gov/vuln/detail/CVE-2026-98745
Affected packages
Git / git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Affected ranges
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced7dde62f0687c8856b6c0660066c7ee83a6a6f033Fixedf2338929c7663859c0c74dd6fef2c0245066f845Fixed2bce6f006cfe0b60e8249fd8d51396d99355cba3Fixed88c1c611552b24658eb61244086691c02be2013bFixede060d9069b49fe55f38057dfe592068014652671
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced6.1.7Fixed6.2
- Type
- GIT
- Repo
- https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
- Events
-
Introduced05458ee3ff82b31a4564836a84ef20d6c233dfc7