nfsd: Reset write verifier when async COPY writeback fails

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89706
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-11 20:19:57 UTC
Updated2026-09-11 20:19:57 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: nfsd: Reset write verifier when async COPY writeback fails Async COPY captures nn->writeverf at request time and reports it to the client via CB_OFFLOAD after the worker kthread completes. When the post-copy vfs_fsync_range() or filemap_check_wb_err() in _nfsd_copy_file_range() reports an error, the worker correctly leaves NFSD4_COPY_F_COMMITTED clear so that CB_OFFLOAD encodes wr_stable_how as NFS_UNSTABLE, but the server's write verifier is not rotated. A client that receives NFS_UNSTABLE in CB_OFFLOAD follows up with COMMIT to make the copied data durable. With the verifier unchanged, COMMIT returns the same value the client just received via CB_OFFLOAD, and the client concludes the copy is durable -- silently dropping the data whose writeback in fact failed. This violates the UNSTABLE+COMMIT durability contract (RFC 7862 section 15.1, RFC 8881 section 18.32) and matches the bug just fixed in nfsd_vfs_write() and nfsd_commit(). Rotate nn->writeverf at the writeback-failure site. The async COPY worker has no svc_rqst, so commit_reset_write_verifier() is not available here; calling nfsd_reset_write_verifier() directly mirrors the trace-less reset already used by nfsd_file_check_write_error() for the same purpose. Filter out -EAGAIN and -ESTALE, matching commit_reset_write_verifier(), since neither indicates a durable-storage failure.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d 31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0 git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d 591134e059e3456180244a826d6917cdc183140b git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d bf0cd31a9abcb728c17d79b4c2cc533612a8b6af git Not specified
CNA Linux Linux affected eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9 git Not specified
CNA Linux Linux affected 817c6eb975798647c4bbbfc9eb288aa413ec7f65 git Not specified
CNA Linux Linux affected 5.10.220 5.11 semver Not specified
CNA Linux Linux affected 5.14 Not specified
CNA Linux Linux unaffected 5.14 semver Not specified
CNA Linux Linux unaffected 6.12.109 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.50 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.4 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/bf0cd31a9abcb728c17d79b4c2cc533612a8b6af 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/591134e059e3456180244a826d6917cdc183140b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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