CVE-2022-48862 vhost: fix hung thread due to erroneous iotlb entries

2024-07-1612:25:25

Linux

www.cve.org

linux kernel

vhost

vulnerability

EPSS

Percentile

5.1%

JSON

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

vhost: fix hung thread due to erroneous iotlb entries

In vhost_iotlb_add_range_ctx(), range size can overflow to 0 when
start is 0 and last is ULONG_MAX. One instance where it can happen
is when userspace sends an IOTLB message with iova=size=uaddr=0
(vhost_process_iotlb_msg). So, an entry with size = 0, start = 0,
last = ULONG_MAX ends up in the iotlb. Next time a packet is sent,
iotlb_access_ok() loops indefinitely due to that erroneous entry.

Call Trace:
 &lt;TASK&gt;
 iotlb_access_ok+0x21b/0x3e0 drivers/vhost/vhost.c:1340
 vq_meta_prefetch+0xbc/0x280 drivers/vhost/vhost.c:1366
 vhost_transport_do_send_pkt+0xe0/0xfd0 drivers/vhost/vsock.c:104
 vhost_worker+0x23d/0x3d0 drivers/vhost/vhost.c:372
 kthread+0x2e9/0x3a0 kernel/kthread.c:377
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 &lt;/TASK&gt;

Reported by syzbot at:
https://syzkaller.appspot.com/bug?extid=0abd373e2e50d704db87

To fix this, do two things:

Return -EINVAL in vhost_chr_write_iter() when userspace asks to map
a range with size 0.
Fix vhost_iotlb_add_range_ctx() to handle the range [0, ULONG_MAX]
by splitting it into two entries.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/vhost/iotlb.c",
      "drivers/vhost/vhost.c"
    ],
    "versions": [
      {
        "version": "0bbe30668d89",
        "lessThan": "f8d88e86e90e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "0bbe30668d89",
        "lessThan": "d9a747e6b656",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "0bbe30668d89",
        "lessThan": "e2ae38cf3d91",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/vhost/iotlb.c",
      "drivers/vhost/vhost.c"
    ],
    "versions": [
      {
        "version": "5.7",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.7",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.29",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.16.15",
        "lessThanOrEqual": "5.16.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.17",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]