Double Free Affecting bpftool package, versions <0:4.18.0-553.16.1.el8_10


Severity

Recommended
high

Based on CentOS security rating

    Threat Intelligence

    EPSS
    0.04% (15th percentile)

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  • Snyk ID SNYK-CENTOS8-BPFTOOL-6545007
  • published 4 Apr 2024
  • disclosed 3 Apr 2024

How to fix?

Upgrade Centos:8 bpftool to version 0:4.18.0-553.16.1.el8_10 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream bpftool package and not the bpftool package as distributed by Centos. See How to fix? for Centos:8 relevant fixed versions and status.

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

ext4: fix double-free of blocks due to wrong extents moved_len

In ext4_move_extents(), moved_len is only updated when all moves are successfully executed, and only discards orig_inode and donor_inode preallocations when moved_len is not zero. When the loop fails to exit after successfully moving some extents, moved_len is not updated and remains at 0, so it does not discard the preallocations.

If the moved extents overlap with the preallocated extents, the overlapped extents are freed twice in ext4_mb_release_inode_pa() and ext4_process_freed_data() (as described in commit 94d7c16cbbbd ("ext4: Fix double-free of blocks with EXT4_IOC_MOVE_EXT")), and bb_free is incremented twice. Hence when trim is executed, a zero-division bug is triggered in mb_update_avg_fragment_size() because bb_free is not zero and bb_fragments is zero.

Therefore, update move_len after each extent move to avoid the issue.

CVSS Scores

version 3.1
Expand this section

Red Hat

5.5 medium
  • 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
Expand this section

SUSE

5.5 medium