linux-cve-announce - CVE-2025-68322: parisc: Avoid crash due to unaligned access in unwinder

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Message-ID: <2025121622-CVE-2025-68322-b034@gregkh>
Date: Tue, 16 Dec 2025 16:44:24 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-68322: parisc: Avoid crash due to unaligned access in unwinder

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

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

parisc: Avoid crash due to unaligned access in unwinder

Guenter Roeck reported this kernel crash on his emulated B160L machine:

Starting network: udhcpc: started, v1.36.1
 Backtrace:
  [<104320d4>] unwind_once+0x1c/0x5c
  [<10434a00>] walk_stackframe.isra.0+0x74/0xb8
  [<10434a6c>] arch_stack_walk+0x28/0x38
  [<104e5efc>] stack_trace_save+0x48/0x5c
  [<105d1bdc>] set_track_prepare+0x44/0x6c
  [<105d9c80>] ___slab_alloc+0xfc4/0x1024
  [<105d9d38>] __slab_alloc.isra.0+0x58/0x90
  [<105dc80c>] kmem_cache_alloc_noprof+0x2ac/0x4a0
  [<105b8e54>] __anon_vma_prepare+0x60/0x280
  [<105a823c>] __vmf_anon_prepare+0x68/0x94
  [<105a8b34>] do_wp_page+0x8cc/0xf10
  [<105aad88>] handle_mm_fault+0x6c0/0xf08
  [<10425568>] do_page_fault+0x110/0x440
  [<10427938>] handle_interruption+0x184/0x748
  [<11178398>] schedule+0x4c/0x190
  BUG: spinlock recursion on CPU#0, ifconfig/2420
  lock: terminate_lock.2+0x0/0x1c, .magic: dead4ead, .owner: ifconfig/2420, .owner_cpu: 0

While creating the stack trace, the unwinder uses the stack pointer to guess
the previous frame to read the previous stack pointer from memory.  The crash
happens, because the unwinder tries to read from unaligned memory and as such
triggers the unalignment trap handler which then leads to the spinlock
recursion and finally to a deadlock.

Fix it by checking the alignment before accessing the memory.

The Linux kernel CVE team has assigned CVE-2025-68322 to this issue.


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

	Fixed in 6.12.58 with commit 9ac1f44723f26881b9fe7e69c7bc25397b879155
	Fixed in 6.17.8 with commit 009270208f76456c2cefcd565da263b90bb2eadb
	Fixed in 6.18 with commit fd9f30d1038ee1624baa17a6ff11effe5f7617cb

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-2025-68322
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/parisc/kernel/unwind.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/9ac1f44723f26881b9fe7e69c7bc25397b879155
	https://git.kernel.org/stable/c/009270208f76456c2cefcd565da263b90bb2eadb
	https://git.kernel.org/stable/c/fd9f30d1038ee1624baa17a6ff11effe5f7617cb