linux-cve-announce - CVE-2022-50738: vhost-vdpa: fix an iotlb memory leak

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Message-ID: <2025122447-CVE-2022-50738-d561@gregkh>
Date: Wed, 24 Dec 2025 14:05:49 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2022-50738: vhost-vdpa: fix an iotlb memory leak

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

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

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

vhost-vdpa: fix an iotlb memory leak

Before commit 3d5698793897 ("vhost-vdpa: introduce asid based IOTLB")
we called vhost_vdpa_iotlb_unmap(v, iotlb, 0ULL, 0ULL - 1) during
release to free all the resources allocated when processing user IOTLB
messages through vhost_vdpa_process_iotlb_update().
That commit changed the handling of IOTLB a bit, and we accidentally
removed some code called during the release.

We partially fixed this with commit 037d4305569a ("vhost-vdpa: call
vhost_vdpa_cleanup during the release") but a potential memory leak is
still there as showed by kmemleak if the application does not send
VHOST_IOTLB_INVALIDATE or crashes:

  unreferenced object 0xffff888007fbaa30 (size 16):
    comm "blkio-bench", pid 914, jiffies 4294993521 (age 885.500s)
    hex dump (first 16 bytes):
      40 73 41 07 80 88 ff ff 00 00 00 00 00 00 00 00  @sA.............
    backtrace:
      [<0000000087736d2a>] kmem_cache_alloc_trace+0x142/0x1c0
      [<0000000060740f50>] vhost_vdpa_process_iotlb_msg+0x68c/0x901 [vhost_vdpa]
      [<0000000083e8e205>] vhost_chr_write_iter+0xc0/0x4a0 [vhost]
      [<000000008f2f414a>] vhost_vdpa_chr_write_iter+0x18/0x20 [vhost_vdpa]
      [<00000000de1cd4a0>] vfs_write+0x216/0x4b0
      [<00000000a2850200>] ksys_write+0x71/0xf0
      [<00000000de8e720b>] __x64_sys_write+0x19/0x20
      [<0000000018b12cbb>] do_syscall_64+0x3f/0x90
      [<00000000986ec465>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Let's fix this calling vhost_vdpa_iotlb_unmap() on the whole range in
vhost_vdpa_remove_as(). We move that call before vhost_dev_cleanup()
since we need a valid v->vdev.mm in vhost_vdpa_pa_unmap().
vhost_iotlb_reset() call can be removed, since vhost_vdpa_iotlb_unmap()
on the whole range removes all the entries.

The kmemleak log reported was observed with a vDPA device that has `use_va`
set to true (e.g. VDUSE). This patch has been tested with both types of
devices.

The Linux kernel CVE team has assigned CVE-2022-50738 to this issue.


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

	Issue introduced in 5.19 with commit 3d5698793897a2b9c0060d899881d1a0591630d5 and fixed in 6.0.19 with commit 4e92cb33bfb51eee5f28bb10846c46f266a4bb67
	Issue introduced in 5.19 with commit 3d5698793897a2b9c0060d899881d1a0591630d5 and fixed in 6.1.5 with commit a2907867e2c86067accd2f011d6f23ee5533aa6c
	Issue introduced in 5.19 with commit 3d5698793897a2b9c0060d899881d1a0591630d5 and fixed in 6.2 with commit c070c1912a83432530cbb4271d5b9b11fa36b67a

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-2022-50738
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/vhost/vdpa.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/4e92cb33bfb51eee5f28bb10846c46f266a4bb67
	https://git.kernel.org/stable/c/a2907867e2c86067accd2f011d6f23ee5533aa6c
	https://git.kernel.org/stable/c/c070c1912a83432530cbb4271d5b9b11fa36b67a