CVE-2026-90212
UnknownSummary
In the Linux kernel on arm64, a bug in EFI runtime services handling occurs when software PAN (CONFIG_ARM64_SW_TTBR0_PAN) is enabled. The fpsimd context management code called from __efi_fpsimd_begin() can be voluntarily preempted, causing an incorrect TTBR0_EL1 value upon return to EFI code and leading to a kernel memory access fault. The fix reorders the fpsimd switch so it occurs before the page-table change.
Risk Assessment
On arm64 systems with software PAN enabled and EFI runtime services support, a kernel Oops and potential system instability may occur. This can result in a crash or failure of EFI runtime services.
Recommendation
Update the Linux kernel to a version containing the fix for this issue. If possible, avoid the CONFIG_ARM64_SW_TTBR0_PAN configuration on machines using EFI runtime services until the update is applied.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: arm64/efi: Avoid voluntary preemption with efi_mm installed Gus reports a bad kernel memory access when using software PAN (CONFIG_ARM64_SW_TTBR0_PAN=y) on a machine with support for EFI runtime services: Unable to handle kernel access to user memory outside uaccess routines at virtual address 00000000f322ff30 Mem abort info: ESR = 0x0000000096000004 FSC = 0x04: level 0 translation fault Internal error: Oops: 0000000096000004 [#1] SMP Workqueue: efi_rts_wq efi_call_rts pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : efi_call_rts+0xd8/0x288 Call trace: efi_call_rts+0xd8/0x288 (P) process_one_work+0x178/0x4f8 worker_thread+0x194/0x328 This is because the fpsimd context management code called from __efi_fpsimd_begin() can preempt voluntarily, returning later to the EFI code with an incorrect value for TTBR0_EL1 thanks to the deferred mm switching used by the software PAN implementation. Since EFI runtime services cannot preempt voluntarily and because the fpsimd switching code does not rely on the TTBR0_EL1 mappings, simply reorder the fpsimd switch so that it occurs before we change the page-table.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS

