Linux Distros のパッチ未適用の脆弱性: CVE-2026-45895
medium Nessus プラグイン ID 317694
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概要
Linux/Unix ホストには、ベンダーにより修正されていないことを示す脆弱性を持つ複数のパッケージがインストールされています。説明
Linux/Unix ホストには、ベンダーが提供するパッチが利用できない脆弱性の影響を受ける複数のパッケージがインストールされています。- Linux カーネルでは、以下の脆弱性が解決されています: quota: fix livelock between quotactl and freeze_super When a filesystem is frozen, quotactl_block() enters a retry loop waiting for the filesystem to thaw. It acquires s_umount, checks the freeze state, drops s_umount and uses sb_start_write() - sb_end_write() pair to wait for the unfreeze. However, this retry loop can trigger a livelock issue, specifically on kernels with preemption disabled. The mechanism is as follows: 1.
freeze_super() sets SB_FREEZE_WRITE and calls sb_wait_write(). 2. sb_wait_write() calls percpu_down_write(), which initiates synchronize_rcu(). 3. Simultaneously, quotactl_block() spins in its retry loop, immediately executing the sb_start_write() - sb_end_write() pair. 4. Because the kernel is non-preemptible and the loop contains no scheduling points, quotactl_block() never yields the CPU. This prevents that CPU from reaching an RCU quiescent state. 5. synchronize_rcu() in the freezer thread waits indefinitely for the quotactl_block() CPU to report a quiescent state. 6. quotactl_block() spins indefinitely waiting for the freezer to advance, which it cannot do as it is blocked on the RCU sync. This results in a hang of the freezer process and 100% CPU usage by the quota process. While this can occur intermittently on multi-core systems, it is reliably reproducing on a node with the following script, running both the freezer and the quota toggle on the same CPU: # mkfs.ext4 -O quota /dev/sda 2g && mkdir a_mount # mount /dev/sda -o quota,usrquota,grpquota a_mount # taskset -c 3 bash -c while true; do xfs_freeze -f a_mount; \ xfs_freeze -u a_mount; done & # taskset -c 3 bash -c while true; do quotaon a_mount; \ quotaoff a_mount; done & Adding cond_resched() to the retry loop fixes the issue. It acts as an RCU quiescent state, allowing synchronize_rcu() in percpu_down_write() to complete. (CVE-2026-45895)
Nessus は、ベンダーによって報告されたパッケージの存在に依存していることに注意してください。
ソリューション
現時点で既知の解決策はありません。参考資料
プラグインの詳細
深刻度: Medium
ID: 317694
ファイル名: unpatched_CVE_2026_45895.nasl
バージョン: 1.1
タイプ: Local
エージェント: unix
ファミリー: Misc.
公開日: 2026/5/29
更新日: 2026/5/29
サポートされているセンサー: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus
リスク情報
VPR
リスクファクター: Medium
スコア: 4.4
脆弱性情報
CPE: p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs-devel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-doc, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-devel, p-cpe:/a:redhat:enterprise_linux:kernel-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-rt, p-cpe:/a:redhat:enterprise_linux:kernel-64k-modules, p-cpe:/a:redhat:enterprise_linux:kernel-modules-extra-matched, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-debug-uki-virt, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules, p-cpe:/a:redhat:enterprise_linux:perf, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-abi-stablelists, p-cpe:/a:redhat:enterprise_linux:kernel-rt-kvm, p-cpe:/a:redhat:enterprise_linux:kernel-tools, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-64k-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-modules-extra, p-cpe:/a:redhat:enterprise_linux:rv, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug, p-cpe:/a:redhat:enterprise_linux:kernel, p-cpe:/a:redhat:enterprise_linux:kernel-devel, p-cpe:/a:redhat:enterprise_linux:kernel-64k-devel, cpe:/o:redhat:enterprise_linux:10, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k, p-cpe:/a:redhat:enterprise_linux:kernel-uki-virt, p-cpe:/a:redhat:enterprise_linux:kernel-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-64k-debug-modules, p-cpe:/a:redhat:enterprise_linux:libperf, p-cpe:/a:redhat:enterprise_linux:kernel-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules, p-cpe:/a:redhat:enterprise_linux:kernel-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-devel, p-cpe:/a:redhat:enterprise_linux:kernel-uki-virt-addons, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-debug, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-core, p-cpe:/a:redhat:enterprise_linux:python3-perf, p-cpe:/a:redhat:enterprise_linux:kernel-debug-devel-matched, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-devel-matched, p-cpe:/a:redhat:enterprise_linux:rtla, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug, p-cpe:/a:redhat:enterprise_linux:kernel-64k-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-64k-core, p-cpe:/a:redhat:enterprise_linux:kernel-64k-devel-matched
必要な KB アイテム: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier
エクスプロイトの容易さ: No known exploits are available
脆弱性公開日: 2026/5/27
参照情報
CVE: CVE-2026-45895