CVE-2024-26704

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    CVE-2024-26704

    Published: 3 Apr 2024Last Modified: 12 Aug 2026

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

    Details: 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.

    References: https://git.kernel.org/stable/c/185eab30486ba3e7bf8b9c2e049c79a06ffd2bc1, https://git.kernel.org/stable/c/2883940b19c38d5884c8626483811acf4d7e148f, https://git.kernel.org/stable/c/55583e899a5357308274601364741a83e78d6ac4, https://git.kernel.org/stable/c/559ddacb90da1d8786dd8ec4fd76bbfa404eaef6, https://git.kernel.org/stable/c/afba9d11320dad5ce222ac8964caf64b7b4bedb1, https://git.kernel.org/stable/c/afbcad9ae7d6d11608399188f03a837451b6b3a1, https://git.kernel.org/stable/c/b4fbb89d722cbb16beaaea234b7230faaaf68c71, https://git.kernel.org/stable/c/d033a555d9a1cf53dbf3301af7199cc4a4c8f537, https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html, https://lists.debian.org/debian-lts-announce/2024/06/msg00020.html, https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/26xxx/CVE-2024-26704.json, https://nvd.nist.gov/vuln/detail/CVE-2024-26704, https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

    Affected packages

    Package

    Name:

    Purl:

    Affected ranges

    Type: GIT

    Events:

    Introduced- fcf6b1b729bcd23f2b49a84fb33ffbb44712ee6a
    Fixed -b4fbb89d722cbb16beaaea234b7230faaaf68c71

    Affected versions

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High
    CVE-2024-26704 | CVE-DB