Use After Free Affecting kernel-rt-debug package, versions *


Severity

Recommended
low

Based on Red Hat Enterprise Linux security rating

    Threat Intelligence

    EPSS
    0.04% (6th percentile)

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  • Snyk ID SNYK-RHEL7-KERNELRTDEBUG-7557911
  • published 24 Jul 2024
  • disclosed 23 Jul 2024

How to fix?

There is no fixed version for RHEL:7 kernel-rt-debug.

NVD Description

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

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

filelock: Remove locks reliably when fcntl/close race is detected

When fcntl_setlk() races with close(), it removes the created lock with do_lock_file_wait(). However, LSMs can allow the first do_lock_file_wait() that created the lock while denying the second do_lock_file_wait() that tries to remove the lock. Separately, posix_lock_file() could also fail to remove a lock due to GFP_KERNEL allocation failure (when splitting a range in the middle).

After the bug has been triggered, use-after-free reads will occur in lock_get_status() when userspace reads /proc/locks. This can likely be used to read arbitrary kernel memory, but can't corrupt kernel memory.

Fix it by calling locks_remove_posix() instead, which is designed to reliably get rid of POSIX locks associated with the given file and files_struct and is also used by filp_flush().

CVSS Scores

version 3.1
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NVD

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

5.5 medium
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SUSE

6.3 medium