CVE-2024-27036 Affecting kernel-rt-kvm package, versions *


Severity

Recommended
0.0
medium
0
10

Based on CentOS security rating.

Threat Intelligence

EPSS
0.05% (18th percentile)

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  • Snyk IDSNYK-CENTOS7-KERNELRTKVM-6801686
  • published2 May 2024
  • disclosed1 May 2024

Introduced: 1 May 2024

CVE-2024-27036  (opens in a new tab)

How to fix?

There is no fixed version for Centos:7 kernel-rt-kvm.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-rt-kvm package and not the kernel-rt-kvm package as distributed by Centos. See How to fix? for Centos:7 relevant fixed versions and status.

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

cifs: Fix writeback data corruption

cifs writeback doesn't correctly handle the case where cifs_extend_writeback() hits a point where it is considering an additional folio, but this would overrun the wsize - at which point it drops out of the xarray scanning loop and calls xas_pause(). The problem is that xas_pause() advances the loop counter - thereby skipping that page.

What needs to happen is for xas_reset() to be called any time we decide we don't want to process the page we're looking at, but rather send the request we are building and start a new one.

Fix this by copying and adapting the netfslib writepages code as a temporary measure, with cifs writeback intending to be offloaded to netfslib in the near future.

This also fixes the issue with the use of filemap_get_folios_tag() causing retry of a bunch of pages which the extender already dealt with.

This can be tested by creating, say, a 64K file somewhere not on cifs (otherwise copy-offload may get underfoot), mounting a cifs share with a wsize of 64000, copying the file to it and then comparing the original file and the copy:

    dd if=/dev/urandom of=/tmp/64K bs=64k count=1
    mount //192.168.6.1/test /mnt -o user=...,pass=...,wsize=64000
    cp /tmp/64K /mnt/64K
    cmp /tmp/64K /mnt/64K

Without the fix, the cmp fails at position 64000 (or shortly thereafter).

CVSS Scores

version 3.1