CVE-2025-38586: bpf, arm64: Fix fp initialization for exception boundary

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-08-19 · updated 2026-10-15
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: bpf, arm64: Fix fp initialization for exception boundary In the ARM64 BPF JIT when prog->aux->exception_boundary is set for a BPF program, find_used_callee_regs() is not called because for a program acting as exception boundary, all callee saved registers are saved. find_used_callee_regs() sets `ctx->fp_used = true;` when it sees FP being used in any of the instructions. For programs acting as exception boundary, ctx->fp_used remains false even if frame pointer is used by the program and therefore, FP is not set-up for such programs in the prologue. This can cause the kernel to crash due to a pagefault. Fix it by setting ctx->fp_used = true for exception boundary programs as fp is always saved in such programs.

Affected products

Linux kernel: from 6.12 before 6.12.42; from 6.13 before 6.15.10; from 6.16 before 6.16.1 — fixed in 6.12.42, 6.15.10, 6.16.1

How to fix

Upgrade to a fixed version: Linux kernel 6.12.42, 6.15.10, 6.16.1. Check the vendor advisory for mitigations.

References

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