rbd: eliminate a race in lock_dwork draining on unmap

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Summary

CVECVE-2026-64112
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 16:17:52 UTC
Updated2026-07-20 07:16:42 UTC
DescriptionIn 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().

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected fd22aef8b47cfc068448df65c1183698b0abd815 3427d7ae38337066ce88b68302e285d344ab756b git Not specified
CNA Linux Linux affected fd22aef8b47cfc068448df65c1183698b0abd815 9dcd4f5c99b491c37be90b0bd9988db48225fb75 git Not specified
CNA Linux Linux affected fd22aef8b47cfc068448df65c1183698b0abd815 9400efc76b42c751211974a25c91d2c19c65b01b git Not specified
CNA Linux Linux affected fd22aef8b47cfc068448df65c1183698b0abd815 9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90 git Not specified
CNA Linux Linux affected 4.12 Not specified
CNA Linux Linux unaffected 4.12 semver Not specified
CNA Linux Linux unaffected 6.12.92 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.34 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.11 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/9400efc76b42c751211974a25c91d2c19c65b01b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9dcd4f5c99b491c37be90b0bd9988db48225fb75 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3427d7ae38337066ce88b68302e285d344ab756b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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