CVE-2026-64112rbd: eliminate a race in lock_dwork draining on unmap

Description

In the Linux kernel, the following vulnerability has been resolved: rbd: eliminate a race in lock_dwork draining on unmap Given how rbd_lock_add_request() and rbd_img_exclusive_lock() are written, lock_dwork may be (re)queued more than it's actually needed: for example in case a new I/O request comes in while we are in the middle of rbd_acquire_lock() on behalf of another I/O request. This is expected and with rbd_release_lock() preemptively canceling lock_dwork is benign under normal operation. A more problematic example is maybe_kick_acquire(): if (have_requests || delayed_work_pending(&rbd_dev->lock_dwork)) { dout("%s rbd_dev %p kicking lock_dwork\n", __func__, rbd_dev); mod_delayed_work(rbd_dev->task_wq, &rbd_dev->lock_dwork, 0); } It's not unrealistic for lock_dwork to get canceled right after delayed_work_pending() returns true and for mod_delayed_work() to requeue it right there anyway. This is a classic TOCTOU race. When it comes to unmapping the image, there is an implicit assumption of no self-initiated exclusive lock activity past the point of return from rbd_dev_image_unlock() which unlocks the lock if it happens to be held. This unlock is assumed to be final and lock_dwork (as well as all other exclusive lock tasks, really) isn't expected to get queued again. However, lock_dwork is canceled only in cancel_tasks_sync() (i.e. later in the unmap sequence) and on top of that the cancellation can get in effect nullified by maybe_kick_acquire(). This may result in rbd_acquire_lock() executing after rbd_dev_device_release() and rbd_dev_image_release() run and free and/or reset a bunch of things. One of the possible failure modes then is a violated rbd_assert(rbd_image_format_valid(rbd_dev->image_format)); in rbd_dev_header_info() which is called via rbd_dev_refresh() from rbd_post_acquire_action(). Redo exclusive lock task draining to provide saner semantics and try to meet the assumptions around rbd_dev_image_unlock().

Timeline

Scores

EPSS (exploitation in 30 days)

0.10% · top 99% of all CVEs (14 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.

Affected products

• Linux · Linux

  • affected fd22aef8b47cfc068448df65c1183698b0abd815 – < 3427d7ae38337066ce88b68302e285d344ab756b
  • affected fd22aef8b47cfc068448df65c1183698b0abd815 – < 9dcd4f5c99b491c37be90b0bd9988db48225fb75
  • affected fd22aef8b47cfc068448df65c1183698b0abd815 – < 9400efc76b42c751211974a25c91d2c19c65b01b
  • affected fd22aef8b47cfc068448df65c1183698b0abd815 – < 9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90

• Linux · Linux

  • affected 4.12
  • unaffected < 4.12
  • unaffected 6.12.92 – ≤ 6.12.*
  • unaffected 6.18.34 – ≤ 6.18.*
  • unaffected 7.0.11 – ≤ 7.0.*
  • unaffected 7.1 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-45797 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-64112](https://cveledger.app/badge/CVE-2026-64112.svg)](https://cveledger.app/cve/CVE-2026-64112)

Record last updated 19 Oct 2026, 20:28 UTC.