GHSA-pw2v-cmfh-x2p3 · 深刻度： medium — In the Linux kernel, the following vulnerability has been resolved: btrfs: do not strictly...
In the Linux kernel, the following vulnerability has been resolved: btrfs: do not strictly require dirty metadata threshold for metadata writepages [BUG] There is an internal report that over 1000 processes are waiting at the io_schedule_timeout() of balance_dirty_pages(), causing a system hang and trigger a kernel coredump. The kernel is v6.4 kernel based, but the root problem still applies to any upstream kernel before v6.18. [CAUSE] From Jan Kara for his wisdom on the dirty page balance behavior first. This cgroup dirty limit was what was actually playing the role here because the cgroup had only a small amount of memory and so the dirty limit for it was something like 16MB. Dirty throttling is responsible for enforcing that nobody can dirty (significantly) more dirty memory than there's dirty limit. Thus when a task is dirtying pages it periodically enters into balance_dirty_pages() and we let it sleep there to slow down the dirtying. When the system is over dirty limit already (either globally or within a cgroup of the running task), we will not let the task exit from balance_dirty_pages() until the number of dirty pages drops below the limit. So in this particular case, as I already mentioned, there was a cgroup with relatively small amount of memory and as a result with dirty limit set at 16MB. A task from that cgroup has dirtied about 28MB worth of pages in btrfs btree inode and these were practically the only dirty pages in that cgroup. So that means the only way to reduce the dirty pages of that cgroup is to writeback the dirty pages of btrfs btree inode, and only after that those processes can exit balance_dirty_pages(). Now back to the btrfs part, btree_writepages() is responsible for writing back dirty btree inode pages. The problem here is, there is a btrfs internal threshold that if the btree inode's dirty bytes are below the 32M threshold, it will not do any writeback. This behavior is to batch as much metadata as possible so we won't write back those tree blocks and then later re-COW them again for another modification. This internal 32MiB is higher than the existing dirty page size (28MiB), meaning no writeback will happen, causing a deadlock between btrfs and cgroup: - Btrfs doesn't want to write back btree inode until more dirty pages - Cgroup/MM doesn't want more dirty pages for btrfs btree inode Thus any process touching that btree inode is put into sleep until the number of dirty pages is reduced. Thanks Jan Kara a lot for the analysis of the root cause. [ENHANCEMENT] Since kernel commit b55102826d7d ("btrfs: set AS_KERNEL_FILE on the btree_inode"), btrfs btree inode pages will only be charged to the root cgroup which should have a much larger limit than btrfs' 32MiB threshold. So it should not affect newer kernels. But for all current LTS kernels, they are all affected by this problem, and backporting the whole AS_KERNEL_FILE may not be a good idea. Even for newer kernels I still think it's a good idea to get rid of the internal threshold at btree_writepages(), since for most cases cgroup/MM has a better view of full system memory usage than btrfs' fixed threshold. For internal callers using btrfs_btree_balance_dirty() since that function is already doing internal threshold check, we don't need to bother them. But for external callers of btree_writepages(), just respect their requests and write back whatever they want, ignoring the internal btrfs threshold to avoid such deadlock on btree inode dirty page balancing.
総合評価: CVE-2026-23157 は低リスク（23/100）。CVSS 深刻度は中。悪用される可能性が高い（EPSS 0.12%、2 パーセンタイル） 推奨対応: 悪用情報と EPSS の推移を監視し、必要に応じて優先度を見直してください。
リスクは変動します。再評価に基づき、本ページの表示内容を更新しています。
EPSS は日次で悪用されやすさの相対度合いを推定します。パーセンタイルは採点済み CVE の中での相対位置（高いほど相対的に深刻）を示します。
| # | 日付 | 旧 EPSS スコア | 新 EPSS スコア | Δ（新 − 旧） |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.02% | 0.12% | +0.11% |
| 2 | 2026-02-15 | — | 0.02% | — |
EPSS の全履歴 （全 2 件）
この CVE の CVSS 指標。
| ベーススコア | バージョン | 深刻度 | ベクトル | 悪用しやすさ | 影響 | スコアの出典 |
|---|---|---|---|---|---|---|
| 5.5 | 3.1 | MEDIUM |
|
1.8 | 3.6 | [email protected] |
GHSA-pw2v-cmfh-x2p3 · 深刻度： medium — In the Linux kernel, the following vulnerability has been resolved: btrfs: do not strictly...
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
not yet assigned | CVE-2026-23157 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5, open 1. | https://security-tracker.debian.org/tracker/CVE-2026-23157 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2026-23157 |
suse
|
medium | CVE-2026-23157 severity moderate: SUSE including 222 source package names (2.1.3-6.144:kernel-default-base-6.4.0-41.1.21.18, 2.1.3-7.127:kernel-default-6.4.0-41.1, …), 432 product×package rows across 37 product lines (Container suse/sl-micro/6.0/base-os-container, Container suse/sl-micro/6.0/kvm-os-container, … (37 product lines)): Fixed 407, First Fixed 25. | https://www.suse.com/security/cve/CVE-2026-23157/ |
ubuntu
|
medium | CVE-2026-23157 medium priority: Ubuntu including 157 source packages (linux, linux-allwinner-5.19, …), 1256 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): DNE 871, ignored 173, needed 129, released 83. | https://ubuntu.com/security/CVE-2026-23157 |
| ベンダー | 製品 | バージョン | 生の CPE |
|---|---|---|---|
| linux | linux_kernel | >= 2.6.29, < 6.18.9 | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
| linux | linux_kernel | 6.19 | cpe:2.3:o:linux:linux_kernel:6.19:rc1:*:*:*:*:*:* |
| linux | linux_kernel | 6.19 | cpe:2.3:o:linux:linux_kernel:6.19:rc2:*:*:*:*:*:* |
| linux | linux_kernel | 6.19 | cpe:2.3:o:linux:linux_kernel:6.19:rc3:*:*:*:*:*:* |
| linux | linux_kernel | 6.19 | cpe:2.3:o:linux:linux_kernel:6.19:rc4:*:*:*:*:*:* |
| linux | linux_kernel | 6.19 | cpe:2.3:o:linux:linux_kernel:6.19:rc5:*:*:*:*:*:* |
| linux | linux_kernel | 6.19 | cpe:2.3:o:linux:linux_kernel:6.19:rc6:*:*:*:*:*:* |
| linux | linux_kernel | 6.19 | cpe:2.3:o:linux:linux_kernel:6.19:rc7:*:*:*:*:*:* |