linux-cve-announce - CVE-2024-56624: iommufd: Fix out_fput in iommufd_fault

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Message-ID: <2024122711-CVE-2024-56624-35f7@gregkh>
Date: Fri, 27 Dec 2024 15:51:31 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-56624: iommufd: Fix out_fput in iommufd_fault_alloc()

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

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

iommufd: Fix out_fput in iommufd_fault_alloc()

As fput() calls the file->f_op->release op, where fault obj and ictx are
getting released, there is no need to release these two after fput() one
more time, which would result in imbalanced refcounts:
  refcount_t: decrement hit 0; leaking memory.
  WARNING: CPU: 48 PID: 2369 at lib/refcount.c:31 refcount_warn_saturate+0x60/0x230
  Call trace:
   refcount_warn_saturate+0x60/0x230 (P)
   refcount_warn_saturate+0x60/0x230 (L)
   iommufd_fault_fops_release+0x9c/0xe0 [iommufd]
  ...
  VFS: Close: file count is 0 (f_op=iommufd_fops [iommufd])
  WARNING: CPU: 48 PID: 2369 at fs/open.c:1507 filp_flush+0x3c/0xf0
  Call trace:
   filp_flush+0x3c/0xf0 (P)
   filp_flush+0x3c/0xf0 (L)
   __arm64_sys_close+0x34/0x98
  ...
  imbalanced put on file reference count
  WARNING: CPU: 48 PID: 2369 at fs/file.c:74 __file_ref_put+0x100/0x138
  Call trace:
   __file_ref_put+0x100/0x138 (P)
   __file_ref_put+0x100/0x138 (L)
   __fput_sync+0x4c/0xd0

Drop those two lines to fix the warnings above.

The Linux kernel CVE team has assigned CVE-2024-56624 to this issue.

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

	Issue introduced in 6.11 with commit 07838f7fd529c8a6de44b601d4b7057e6c8d36ed and fixed in 6.12.5 with commit 2b3f30c8edbf9a122ce01f13f0f41fbca5f1d41d
	Issue introduced in 6.11 with commit 07838f7fd529c8a6de44b601d4b7057e6c8d36ed and fixed in 6.13-rc2 with commit af7f4780514f850322b2959032ecaa96e4b26472

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-2024-56624
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/fault.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/2b3f30c8edbf9a122ce01f13f0f41fbca5f1d41d
	https://git.kernel.org/stable/c/af7f4780514f850322b2959032ecaa96e4b26472