linux-cve-announce - CVE-2024-56668: iommu/vt-d: Fix qi_batch NULL pointer with nested parent domain

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Message-ID: <2024122754-CVE-2024-56668-0d8d@gregkh>
Date: Fri, 27 Dec 2024 16:07:05 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56668: iommu/vt-d: Fix qi_batch NULL pointer with nested parent domain

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

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

iommu/vt-d: Fix qi_batch NULL pointer with nested parent domain

The qi_batch is allocated when assigning cache tag for a domain. While
for nested parent domain, it is missed. Hence, when trying to map pages
to the nested parent, NULL dereference occurred. Also, there is potential
memleak since there is no lock around domain->qi_batch allocation.

To solve it, add a helper for qi_batch allocation, and call it in both
the __cache_tag_assign_domain() and __cache_tag_assign_parent_domain().

  BUG: kernel NULL pointer dereference, address: 0000000000000200
  #PF: supervisor read access in kernel mode
  #PF: error_code(0x0000) - not-present page
  PGD 8104795067 P4D 0
  Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI
  CPU: 223 UID: 0 PID: 4357 Comm: qemu-system-x86 Not tainted 6.13.0-rc1-00028-g4b50c3c3b998-dirty #2632
  Call Trace:
   ? __die+0x24/0x70
   ? page_fault_oops+0x80/0x150
   ? do_user_addr_fault+0x63/0x7b0
   ? exc_page_fault+0x7c/0x220
   ? asm_exc_page_fault+0x26/0x30
   ? cache_tag_flush_range_np+0x13c/0x260
   intel_iommu_iotlb_sync_map+0x1a/0x30
   iommu_map+0x61/0xf0
   batch_to_domain+0x188/0x250
   iopt_area_fill_domains+0x125/0x320
   ? rcu_is_watching+0x11/0x50
   iopt_map_pages+0x63/0x100
   iopt_map_common.isra.0+0xa7/0x190
   iopt_map_user_pages+0x6a/0x80
   iommufd_ioas_map+0xcd/0x1d0
   iommufd_fops_ioctl+0x118/0x1c0
   __x64_sys_ioctl+0x93/0xc0
   do_syscall_64+0x71/0x140
   entry_SYSCALL_64_after_hwframe+0x76/0x7e

The Linux kernel CVE team has assigned CVE-2024-56668 to this issue.


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

	Issue introduced in 6.12 with commit 705c1cdf1e73c4c727bbfc8775434e6dd36e8baf and fixed in 6.12.6 with commit ffd774c34774fd4cc0e9cf2976595623a6c3a077
	Issue introduced in 6.12 with commit 705c1cdf1e73c4c727bbfc8775434e6dd36e8baf and fixed in 6.13-rc3 with commit 74536f91962d5f6af0a42414773ce61e653c10ee

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-2024-56668
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/iommu/intel/cache.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/ffd774c34774fd4cc0e9cf2976595623a6c3a077
	https://git.kernel.org/stable/c/74536f91962d5f6af0a42414773ce61e653c10ee