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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <2025081915-CVE-2025-38586-789b@gregkh>
Date: Tue, 19 Aug 2025 19:18:32 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-38586: bpf, arm64: Fix fp initialization for exception boundary

From: Greg Kroah-Hartman <gregkh@...nel.org>

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.

The Linux kernel CVE team has assigned CVE-2025-38586 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.12 with commit 5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff and fixed in 6.12.42 with commit 0dbef493cae7d451f740558665893c000adb2321
	Issue introduced in 6.12 with commit 5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff and fixed in 6.15.10 with commit e23184725dbb72d5d02940222eee36dbba2aa422
	Issue introduced in 6.12 with commit 5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff and fixed in 6.16.1 with commit 1ce30231e0a2c8c361ee5f8f7f265fc17130adce
	Issue introduced in 6.12 with commit 5d4fa9ec5643a5c75d3c1e6abf50fb9284caf1ff and fixed in 6.17-rc1 with commit b114fcee766d5101eada1aca7bb5fd0a86c89b35

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-38586
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	arch/arm64/net/bpf_jit_comp.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/0dbef493cae7d451f740558665893c000adb2321
	https://git.kernel.org/stable/c/e23184725dbb72d5d02940222eee36dbba2aa422
	https://git.kernel.org/stable/c/1ce30231e0a2c8c361ee5f8f7f265fc17130adce
	https://git.kernel.org/stable/c/b114fcee766d5101eada1aca7bb5fd0a86c89b35