linux-cve-announce - CVE-2025-39936: crypto: ccp - Always pass in an error pointer to __sev_platform_shutdown

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Message-ID: <2025100417-CVE-2025-39936-840a@gregkh>
Date: Sat,  4 Oct 2025 09:33:20 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-39936: crypto: ccp - Always pass in an error pointer to __sev_platform_shutdown_locked()

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

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

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

crypto: ccp - Always pass in an error pointer to __sev_platform_shutdown_locked()

When

  9770b428b1a2 ("crypto: ccp - Move dev_info/err messages for SEV/SNP init and shutdown")

moved the error messages dumping so that they don't need to be issued by
the callers, it missed the case where __sev_firmware_shutdown() calls
__sev_platform_shutdown_locked() with a NULL argument which leads to
a NULL ptr deref on the shutdown path, during suspend to disk:

  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 0 P4D 0
  Oops: Oops: 0000 [#1] SMP NOPTI
  CPU: 0 UID: 0 PID: 983 Comm: hib.sh Not tainted 6.17.0-rc4+ #1 PREEMPT(voluntary)
  Hardware name: Supermicro Super Server/H12SSL-i, BIOS 2.5 09/08/2022
  RIP: 0010:__sev_platform_shutdown_locked.cold+0x0/0x21 [ccp]

That rIP is:

  00000000000006fd <__sev_platform_shutdown_locked.cold>:
   6fd:   8b 13                   mov    (%rbx),%edx
   6ff:   48 8b 7d 00             mov    0x0(%rbp),%rdi
   703:   89 c1                   mov    %eax,%ecx

  Code: 74 05 31 ff 41 89 3f 49 8b 3e 89 ea 48 c7 c6 a0 8e 54 a0 41 bf 92 ff ff ff e8 e5 2e 09 e1 c6 05 2a d4 38 00 01 e9 26 af ff ff <8b> 13 48 8b 7d 00 89 c1 48 c7 c6 18 90 54 a0 89 44 24 04 e8 c1 2e
  RSP: 0018:ffffc90005467d00 EFLAGS: 00010282
  RAX: 00000000ffffff92 RBX: 0000000000000000 RCX: 0000000000000000
  			     ^^^^^^^^^^^^^^^^
and %rbx is nice and clean.

  Call Trace:
   <TASK>
   __sev_firmware_shutdown.isra.0
   sev_dev_destroy
   psp_dev_destroy
   sp_destroy
   pci_device_shutdown
   device_shutdown
   kernel_power_off
   hibernate.cold
   state_store
   kernfs_fop_write_iter
   vfs_write
   ksys_write
   do_syscall_64
   entry_SYSCALL_64_after_hwframe

Pass in a pointer to the function-local error var in the caller.

With that addressed, suspending the ccp shows the error properly at
least:

  ccp 0000:47:00.1: sev command 0x2 timed out, disabling PSP
  ccp 0000:47:00.1: SEV: failed to SHUTDOWN error 0x0, rc -110
  SEV-SNP: Leaking PFN range 0x146800-0x146a00
  SEV-SNP: PFN 0x146800 unassigned, dumping non-zero entries in 2M PFN region: [0x146800 - 0x146a00]
  ...
  ccp 0000:47:00.1: SEV-SNP firmware shutdown failed, rc -16, error 0x0
  ACPI: PM: Preparing to enter system sleep state S5
  kvm: exiting hardware virtualization
  reboot: Power down

Btw, this driver is crying to be cleaned up to pass in a proper I/O
struct which can be used to store information between the different
functions, otherwise stuff like that will happen in the future again.

The Linux kernel CVE team has assigned CVE-2025-39936 to this issue.


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

	Issue introduced in 6.16 with commit 9770b428b1a28360663f1f5e524ee458b4cf454b and fixed in 6.16.9 with commit bc509293c9d4f4f74e776f4a0bbb61f63c041938
	Issue introduced in 6.16 with commit 9770b428b1a28360663f1f5e524ee458b4cf454b and fixed in 6.17 with commit 46834d90a9a13549264b9581067d8f746b4b36cc

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-2025-39936
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:
	drivers/crypto/ccp/sev-dev.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/bc509293c9d4f4f74e776f4a0bbb61f63c041938
	https://git.kernel.org/stable/c/46834d90a9a13549264b9581067d8f746b4b36cc