btrfs: fix racy bitfield write in btrfs_clear_space_info_ful…(CVE-2025-68358)

概要

btrfs: fix racy bitfield write in btrfs_clear_space_info_full()

原文の説明

取得元が公開している説明をそのまま載せています (多くは英語)。

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

btrfs: fix racy bitfield write in btrfs_clear_space_info_full()

From the memory-barriers.txt document regarding memory barrier ordering
guarantees:

(*) These guarantees do not apply to bitfields, because compilers often
generate code to modify these using non-atomic read-modify-write
sequences. Do not attempt to use bitfields to synchronize parallel
algorithms.

(*) Even in cases where bitfields are protected by locks, all fields
in a given bitfield must be protected by one lock. If two fields
in a given bitfield are protected by different locks, the compiler's
non-atomic read-modify-write sequences can cause an update to one
field to corrupt the value of an adjacent field.

btrfs_space_info has a bitfield sharing an underlying word consisting of
the fields full, chunk_alloc, and flush:

struct btrfs_space_info {
struct btrfs_fs_info * fs_info; /* 0 8 /
struct btrfs_space_info * parent; / 8 8 /
...
int clamp; / 172 4 /
unsigned int full:1; / 176: 0 4 /
unsigned int chunk_alloc:1; / 176: 1 4 /
unsigned int flush:1; / 176: 2 4 */
...

Therefore, to be safe from parallel read-modify-writes losing a write to
one of the bitfie…

出典: OSV.dev (Open Source Vulnerabilities) NVD OSV

影響パッケージ

Linux Kernel

[{"type":"ECOSYSTEM","events":[{"introduced":"4.8.0"},{"fixed":"5.15.201"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.164"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.124"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.68"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.17.13"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.18.0"},{"fixed":"6.18.2"}]}]

ディストリビューション別の修正状況

各ディストリビューションが公開している、この CVE の修正パッケージ

BellSoft Alpaquita BELL-CVE-2025-68358 linux-lts 修正版: 6.1.164-r0
Debian DEBIAN-CVE-2025-68358 linux
Ubuntu UBUNTU-CVE-2025-68358 linux-azure

概要

原文の説明

影響パッケージ

ディストリビューション別の修正状況

参照URL