Subject: CVE-2024-26786: iommufd: Fix iopt_access_list_id overwrite bug

From: Greg Kroah-Hartman <[email-masked]>

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

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

iommufd: Fix iopt_access_list_id overwrite bug

Syzkaller reported the following WARN_ON:
  WARNING: CPU: 1 PID: 4738 at drivers/iommu/iommufd/io_pagetable.c:1360

  Call Trace:
   iommufd_access_change_ioas+0x2fe/0x4e0
   iommufd_access_destroy_object+0x50/0xb0
   iommufd_object_remove+0x2a3/0x490
   iommufd_object_destroy_user
   iommufd_access_destroy+0x71/0xb0
   iommufd_test_staccess_release+0x89/0xd0
   __fput+0x272/0xb50
   __fput_sync+0x4b/0x60
   __do_sys_close
   __se_sys_close
   __x64_sys_close+0x8b/0x110
   do_syscall_x64

The mismatch between the access pointer in the list and the passed-in
pointer is resulting from an overwrite of access->iopt_access_list_id, in
iopt_add_access(). Called from iommufd_access_change_ioas() when
xa_alloc() succeeds but iopt_calculate_iova_alignment() fails.

Add a new_id in iopt_add_access() and only update iopt_access_list_id when
returning successfully.

The Linux kernel CVE team has assigned CVE-2024-26786 to this issue.

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

	Issue introduced in 6.6 with commit 9227da7816dd and fixed in 6.6.21 with commit f1fb745ee0a6
	Issue introduced in 6.6 with commit 9227da7816dd and fixed in 6.7.9 with commit 9526a46cc0c3
	Issue introduced in 6.6 with commit 9227da7816dd and fixed in 6.8 with commit aeb004c0cd69

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-2024-26786
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/iommufd/io_pagetable.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/f1fb745ee0a6fe43f1d84ec369c7e6af2310fda9
	https://git.kernel.org/stable/c/9526a46cc0c378d381560279bea9aa34c84298a0
	https://git.kernel.org/stable/c/aeb004c0cd6958e910123a1607634401009c9539