CVE-2023-52786 Affecting kernel-rt-kvm package, versions *


Severity

low

    Threat Intelligence

    EPSS
    0.05% (16th percentile)

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  • Snyk ID SNYK-CENTOS7-KERNELRTKVM-7079112
  • published 23 May 2024
  • disclosed 21 May 2024

Introduced: 21 May 2024

New CVE-2023-52786 Open this link 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:

ext4: fix racy may inline data check in dio write

syzbot reports that the following warning from ext4_iomap_begin() triggers as of the commit referenced below:

    if (WARN_ON_ONCE(ext4_has_inline_data(inode)))
            return -ERANGE;

This occurs during a dio write, which is never expected to encounter an inode with inline data. To enforce this behavior, ext4_dio_write_iter() checks the current inline state of the inode and clears the MAY_INLINE_DATA state flag to either fall back to buffered writes, or enforce that any other writers in progress on the inode are not allowed to create inline data.

The problem is that the check for existing inline data and the state flag can span a lock cycle. For example, if the ilock is originally locked shared and subsequently upgraded to exclusive, another writer may have reacquired the lock and created inline data before the dio write task acquires the lock and proceeds.

The commit referenced below loosens the lock requirements to allow some forms of unaligned dio writes to occur under shared lock, but AFAICT the inline data check was technically already racy for any dio write that would have involved a lock cycle. Regardless, lift clearing of the state bit to the same lock critical section that checks for preexisting inline data on the inode to close the race.

CVSS Scores

version 3.1
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Snyk

5.5 low
  • Attack Vector (AV)
    Local
  • Attack Complexity (AC)
    Low
  • Privileges Required (PR)
    Low
  • User Interaction (UI)
    None
  • Scope (S)
    Unchanged
  • Confidentiality (C)
    None
  • Integrity (I)
    None
  • Availability (A)
    High
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Red Hat

5.5 medium