CVE-2026-64112 (GCVE-0-2026-64112)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:40 – Updated: 2026-07-20 13:43
VLAI
Title
rbd: eliminate a race in lock_dwork draining on unmap
Summary
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().
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: fd22aef8b47cfc068448df65c1183698b0abd815 , < 3427d7ae38337066ce88b68302e285d344ab756b (git)
Affected: fd22aef8b47cfc068448df65c1183698b0abd815 , < 9dcd4f5c99b491c37be90b0bd9988db48225fb75 (git)
Affected: fd22aef8b47cfc068448df65c1183698b0abd815 , < 9400efc76b42c751211974a25c91d2c19c65b01b (git)
Affected: fd22aef8b47cfc068448df65c1183698b0abd815 , < 9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90 (git)
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Linux Linux Affected: 4.12
Unaffected: 0 , < 4.12 (semver)
Unaffected: 6.12.92 , ≤ 6.12.* (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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{
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrbd: eliminate a race in lock_dwork draining on unmap\n\nGiven how rbd_lock_add_request() and rbd_img_exclusive_lock() are\nwritten, lock_dwork may be (re)queued more than it\u0027s actually needed:\nfor example in case a new I/O request comes in while we are in the\nmiddle of rbd_acquire_lock() on behalf of another I/O request.  This is\nexpected and with rbd_release_lock() preemptively canceling lock_dwork\nis benign under normal operation.\n\nA more problematic example is maybe_kick_acquire():\n\n    if (have_requests || delayed_work_pending(\u0026rbd_dev-\u003elock_dwork)) {\n            dout(\"%s rbd_dev %p kicking lock_dwork\\n\", __func__, rbd_dev);\n            mod_delayed_work(rbd_dev-\u003etask_wq, \u0026rbd_dev-\u003elock_dwork, 0);\n    }\n\nIt\u0027s not unrealistic for lock_dwork to get canceled right after\ndelayed_work_pending() returns true and for mod_delayed_work() to\nrequeue it right there anyway.  This is a classic TOCTOU race.\n\nWhen it comes to unmapping the image, there is an implicit assumption\nof no self-initiated exclusive lock activity past the point of return\nfrom rbd_dev_image_unlock() which unlocks the lock if it happens to be\nheld.  This unlock is assumed to be final and lock_dwork (as well as\nall other exclusive lock tasks, really) isn\u0027t expected to get queued\nagain.  However, lock_dwork is canceled only in cancel_tasks_sync()\n(i.e. later in the unmap sequence) and on top of that the cancellation\ncan get in effect nullified by maybe_kick_acquire().  This may result\nin rbd_acquire_lock() executing after rbd_dev_device_release() and\nrbd_dev_image_release() run and free and/or reset a bunch of things.\nOne of the possible failure modes then is a violated\n\n    rbd_assert(rbd_image_format_valid(rbd_dev-\u003eimage_format));\n\nin rbd_dev_header_info() which is called via rbd_dev_refresh() from\nrbd_post_acquire_action().\n\nRedo exclusive lock task draining to provide saner semantics and try\nto meet the assumptions around rbd_dev_image_unlock()."
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This is\\nexpected and with rbd_release_lock() preemptively canceling lock_dwork\\nis benign under normal operation.\\n\\nA more problematic example is maybe_kick_acquire():\\n\\n    if (have_requests || delayed_work_pending(\u0026rbd_dev-\u003elock_dwork)) {\\n            dout(\\\"%s rbd_dev %p kicking lock_dwork\\\\n\\\", __func__, rbd_dev);\\n            mod_delayed_work(rbd_dev-\u003etask_wq, \u0026rbd_dev-\u003elock_dwork, 0);\\n    }\\n\\nIt\u0027s not unrealistic for lock_dwork to get canceled right after\\ndelayed_work_pending() returns true and for mod_delayed_work() to\\nrequeue it right there anyway.  This is a classic TOCTOU race.\\n\\nWhen it comes to unmapping the image, there is an implicit assumption\\nof no self-initiated exclusive lock activity past the point of return\\nfrom rbd_dev_image_unlock() which unlocks the lock if it happens to be\\nheld.  This unlock is assumed to be final and lock_dwork (as well as\\nall other exclusive lock tasks, really) isn\u0027t expected to get queued\\nagain.  However, lock_dwork is canceled only in cancel_tasks_sync()\\n(i.e. later in the unmap sequence) and on top of that the cancellation\\ncan get in effect nullified by maybe_kick_acquire().  This may result\\nin rbd_acquire_lock() executing after rbd_dev_device_release() and\\nrbd_dev_image_release() run and free and/or reset a bunch of things.\\nOne of the possible failure modes then is a violated\\n\\n    rbd_assert(rbd_image_format_valid(rbd_dev-\u003eimage_format));\\n\\nin rbd_dev_header_info() which is called via rbd_dev_refresh() from\\nrbd_post_acquire_action().\\n\\nRedo exclusive lock task draining to provide saner semantics and try\\nto meet the assumptions around rbd_dev_image_unlock().\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"drivers/block/rbd.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"fd22aef8b47cfc068448df65c1183698b0abd815\",\"lessThan\":\"3427d7ae38337066ce88b68302e285d344ab756b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"fd22aef8b47cfc068448df65c1183698b0abd815\",\"lessThan\":\"9dcd4f5c99b491c37be90b0bd9988db48225fb75\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"fd22aef8b47cfc068448df65c1183698b0abd815\",\"lessThan\":\"9400efc76b42c751211974a25c91d2c19c65b01b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"fd22aef8b47cfc068448df65c1183698b0abd815\",\"lessThan\":\"9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"drivers/block/rbd.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"4.12\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"4.12\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.92\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.34\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0.11\",\"lessThanOrEqual\":\"7.0.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/3427d7ae38337066ce88b68302e285d344ab756b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9400efc76b42c751211974a25c91d2c19c65b01b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9dcd4f5c99b491c37be90b0bd9988db48225fb75\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-20T15:42:02+00:00",
      "cve": "CVE-2026-64112",
      "id": "CVE-2026-64112",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "260",
      "product_status:known_not_affected": "14",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: rbd: eliminate a race in lock_dwork draining on unmap",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64112.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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