ceph: fix num_ops off-by-one when crypto allocation fails
Summary
| CVE | CVE-2026-46066 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-05-27 14:17:27 UTC |
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| Updated | 2026-05-27 14:48:03 UTC |
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| 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. |
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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.
