btrfs: ensure no dirty metadata is written back for an fs with errors

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-40303
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-12-08 01:16:02 UTC
Updated2026-07-30 06:24:27 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: btrfs: ensure no dirty metadata is written back for an fs with errors [BUG] During development of a minor feature (make sure all btrfs_bio::end_io() is called in task context), I noticed a crash in generic/388, where metadata writes triggered new works after btrfs_stop_all_workers(). It turns out that it can even happen without any code modification, just using RAID5 for metadata and the same workload from generic/388 is going to trigger the use-after-free. [CAUSE] If btrfs hits an error, the fs is marked as error, no new transaction is allowed thus metadata is in a frozen state. But there are some metadata modifications before that error, and they are still in the btree inode page cache. Since there will be no real transaction commit, all those dirty folios are just kept as is in the page cache, and they can not be invalidated by invalidate_inode_pages2() call inside close_ctree(), because they are dirty. And finally after btrfs_stop_all_workers(), we call iput() on btree inode, which triggers writeback of those dirty metadata. And if the fs is using RAID56 metadata, this will trigger RMW and queue new works into rmw_workers, which is already stopped, causing warning from queue_work() and use-after-free. [FIX] Add a special handling for write_one_eb(), that if the fs is already in an error state, immediately mark the bbio as failure, instead of really submitting them. Then during close_ctree(), iput() will just discard all those dirty tree blocks without really writing them back, thus no more new jobs for already stopped-and-freed workqueues. The extra discard in write_one_eb() also acts as an extra safenet. E.g. the transaction abort is triggered by some extent/free space tree corruptions, and since extent/free space tree is already corrupted some tree blocks may be allocated where they shouldn't be (overwriting existing tree blocks). In that case writing them back will further corrupting the fs.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001240000 probability, percentile 0.025150000 (date 2026-07-31)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 13e6c37b989859e70b0d73d3f2cb0aa022159b17 066ee13f05fbd82ada01883e51f0695172f98dff git Not specified
CNA Linux Linux affected 13e6c37b989859e70b0d73d3f2cb0aa022159b17 e2b3859067bf012d53c49b3f885fef40624a2c83 git Not specified
CNA Linux Linux affected 13e6c37b989859e70b0d73d3f2cb0aa022159b17 54a5b5a15588e3b0b294df31474d08a2678d4291 git Not specified
CNA Linux Linux affected 13e6c37b989859e70b0d73d3f2cb0aa022159b17 2618849f31e7cf51fadd4a5242458501a6d5b315 git Not specified
CNA Linux Linux affected 3.10 Not specified
CNA Linux Linux unaffected 3.10 semver Not specified
CNA Linux Linux unaffected 6.6.117 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.58 6.12.* semver Not specified
CNA Linux Linux unaffected 6.17.8 6.17.* semver Not specified
CNA Linux Linux unaffected 6.18 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/e2b3859067bf012d53c49b3f885fef40624a2c83 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/54a5b5a15588e3b0b294df31474d08a2678d4291 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2618849f31e7cf51fadd4a5242458501a6d5b315 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/066ee13f05fbd82ada01883e51f0695172f98dff 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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