Skip to main content
cve.nowby Sazabi
← All vulnerabilities
CVE-2026-89706

nfsd: Reset write verifier when async COPY writeback fails

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.270, 5.15.221, 6.1.188, 6.6.157, 6.12.109, and 2 more
None on Exploit-DB, Metasploit or GitHub

Summary

In 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.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 817c6eb975798647c4bbbfc9eb288aa413ec7f65 · fixed in cc5f7cef0659a27c13dd33edd8e2f79257b095c6; From eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d · fixed in c6d2f6372c7e0f76b9c148ff7696aec64da0b5b7; From eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d · fixed in 8a08ffe73eb2aa6bc6f88763da7e2b55bab6493a; From eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d · fixed in 6b13d26cc21b6320a3c61d5e4cee2ce9a589b181; From eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d · fixed in 31d4d0a62ec4bafbcdbad142f11ab1f90794b1d0; From eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d · fixed in 591134e059e3456180244a826d6917cdc183140b; From eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d · fixed in bf0cd31a9abcb728c17d79b4c2cc533612a8b6af; From eac0b17a77fbd763d305a5eaa4fd1119e5a0fe0d · fixed in f5cb2276954cb80987a93ef9f9dfbfdbfc0f10b9; From 5.10.220 · fixed in 5.10.270

  • Linux Linux

    5.14

  • KernelLinux

    fixed in 5.10.270; From 5.11.0 · fixed in 5.15.221; From 5.14.0 · fixed in 6.1.188; From 5.16.0 · fixed in 6.6.157; From 6.2.0 · fixed in 6.12.109; From 6.7.0 · fixed in 6.18.50; From 6.13.0 · fixed in 7.2.4

References 8

git.kernel.org