ceph: fix num_ops off-by-one when crypto allocation fails
Summary
| CVE | CVE-2026-46066 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-05-27 14:17:27 UTC |
| Updated | 2026-05-27 14:48:03 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: ceph: fix num_ops off-by-one when crypto allocation fails move_dirty_folio_in_page_array() may fail if the file is encrypted, the dirty folio is not the first in the batch, and it fails to allocate a bounce buffer to hold the ciphertext. When that happens, ceph_process_folio_batch() simply redirties the folio and flushes the current batch -- it can retry that folio in a future batch. However, if this failed folio is not contiguous with the last folio that did make it into the batch, then ceph_process_folio_batch() has already incremented `ceph_wbc->num_ops`; because it doesn't follow through and add the discontiguous folio to the array, ceph_submit_write() -- which expects that `ceph_wbc->num_ops` accurately reflects the number of contiguous ranges (and therefore the required number of "write extent" ops) in the writeback -- will panic the kernel: BUG_ON(ceph_wbc->op_idx + 1 != req->r_num_ops); This issue can be reproduced on affected kernels by writing to fscrypt-enabled CephFS file(s) with a 4KiB-written/4KiB-skipped/repeat pattern (total filesize should not matter) and gradually increasing the system's memory pressure until a bounce buffer allocation fails. Fix this crash by decrementing `ceph_wbc->num_ops` back to the correct value when move_dirty_folio_in_page_array() fails, but the folio already started counting a new (i.e. still-empty) extent. The defect corrected by this patch has existed since 2022 (see first `Fixes:`), but another bug blocked multi-folio encrypted writeback until recently (see second `Fixes:`). The second commit made it into 6.18.16, 6.19.6, and 7.0-rc1, unmasking the panic in those versions. This patch therefore fixes a regression (panic) introduced by cac190c7674f. |
Risk And Classification
EPSS: 0.000170000 probability, percentile 0.042650000 (date 2026-06-01)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected d55207717ded95c8f2760a30e93319fa313186e6 6200f41d6fcf2ac7e24866431e381cbc914560e4 git | Not specified |
| CNA | Linux | Linux | affected d55207717ded95c8f2760a30e93319fa313186e6 ba12c1e578890f6337a415b7dedf476c6d455105 git | Not specified |
| CNA | Linux | Linux | affected d55207717ded95c8f2760a30e93319fa313186e6 a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842 git | Not specified |
| CNA | Linux | Linux | affected 6.6 | Not specified |
| CNA | Linux | Linux | unaffected 6.6 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.30 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.0.4 7.0.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1-rc1 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/ba12c1e578890f6337a415b7dedf476c6d455105 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/6200f41d6fcf2ac7e24866431e381cbc914560e4 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.