Loop with Unreachable Exit Condition ('Infinite Loop') Affecting kernel-rt-debug-kvm package, versions *


Severity

Recommended
0.0
medium
0
10

Based on Red Hat Enterprise Linux security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-RHEL8-KERNELRTDEBUGKVM-7504467
  • published17 Jul 2024
  • disclosed16 Jul 2024

Introduced: 16 Jul 2024

CVE-2022-48862  (opens in a new tab)
CWE-835  (opens in a new tab)

How to fix?

There is no fixed version for RHEL:8 kernel-rt-debug-kvm.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-debug-kvm package and not the kernel-rt-debug-kvm package as distributed by RHEL. See How to fix? for RHEL:8 relevant fixed versions and status.

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:
 <TASK>
 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
 </TASK>

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

To fix this, do two things:

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

CVSS Scores

version 3.1