Homepage

Off-by-one Error The advisory has been revoked - it doesn't affect any version of package perf  (opens in a new tab)

Threat Intelligence

EPSS
0.12% (2nd percentile)

Do your applications use this vulnerable package?

In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.

Test your applications
  • Snyk IDSNYK-RHEL10-PERF-16924273
  • published28 May 2026
  • disclosed27 May 2026
Report a new vulnerability Found a mistake?

Introduced: 27 May 2026

CVE-2026-46066  (opens in a new tab)
CWE-193  (opens in a new tab)

Amendment

The Red Hat security team deemed this advisory irrelevant for RHEL:10.

NVD Description

Note: Versions mentioned in the description apply only to the upstream perf package and not the perf package as distributed by RHEL.

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.