{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64112", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.035Z", "datePublished": "2026-07-19T15:40:13.652Z", "dateUpdated": "2026-08-05T12:39:21.112Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:39:21.112Z" }, "descriptions": [ { "lang": "en", "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's 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(&rbd_dev->lock_dwork)) {\n dout(\"%s rbd_dev %p kicking lock_dwork\\n\", __func__, rbd_dev);\n mod_delayed_work(rbd_dev->task_wq, &rbd_dev->lock_dwork, 0);\n }\n\nIt's 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't 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->image_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()." } ], "metrics": [ { "cvssV3_1": { "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" }, "scenarios": [ { "lang": "en", "value": "AV:L - Exploitation requires writing to /sys/bus/rbd/remove (or the equivalent error-path teardown during map), which is a local sysfs syscall path; network-delivered Ceph lock notifications can assist the race but cannot complete exploitation without this local unmap action.\nAC:L - The attacker controls both sides of the TOCTOU race by concurrently unmapping the device (sysfs remove) while driving lock activity through block I/O or lock-notification handling, making the race winnable with repeated attempts.\nPR:L - Both map and unmap operations require CAP_SYS_ADMIN, which is obtainable by an unprivileged user via user namespaces (unshare -Urn); per kernel CNA guidance this is PR:L rather than PR:H.\nUI:N - No victim interaction is required; the attacker can trigger the race programmatically through concurrent sysfs unmap and I/O or lock-notification activity.\nS:U - Impact is confined to kernel memory corruption and crash on the host running the RBD client; it does not cross a VM, container, or IOMMU security boundary.\nC:H - The bug allows rbd_acquire_lock() to operate on an rbd_device after rbd_dev_image_release() has freed and reset fields, constituting a use-after-free that can expose or dereference freed kernel heap data.\nI:H - Use-after-free on rbd_device and associated header structures provides memory corruption primitives that could be leveraged for arbitrary kernel writes or control-flow hijacking, not merely a clean crash.\nA:H - A confirmed failure mode is rbd_assert() triggering BUG() (kernel panic), and the underlying UAF can also cause oops or hang during post-teardown lock acquisition." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/block/rbd.c" ], "versions": [ { "version": "fd22aef8b47cfc068448df65c1183698b0abd815", "lessThan": "3427d7ae38337066ce88b68302e285d344ab756b", "status": "affected", "versionType": "git" }, { "version": "fd22aef8b47cfc068448df65c1183698b0abd815", "lessThan": "9dcd4f5c99b491c37be90b0bd9988db48225fb75", "status": "affected", "versionType": "git" }, { "version": "fd22aef8b47cfc068448df65c1183698b0abd815", "lessThan": "9400efc76b42c751211974a25c91d2c19c65b01b", "status": "affected", "versionType": "git" }, { "version": "fd22aef8b47cfc068448df65c1183698b0abd815", "lessThan": "9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/block/rbd.c" ], "versions": [ { "version": "4.12", "status": "affected" }, { "version": "0", "lessThan": "4.12", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.92", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.34", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.11", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "6.12.92" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "6.18.34" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "7.0.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.12", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3427d7ae38337066ce88b68302e285d344ab756b" }, { "url": "https://git.kernel.org/stable/c/9dcd4f5c99b491c37be90b0bd9988db48225fb75" }, { "url": "https://git.kernel.org/stable/c/9400efc76b42c751211974a25c91d2c19c65b01b" }, { "url": "https://git.kernel.org/stable/c/9fc75b71fdd38465c76c6f6a884cdd4ae3c72d90" } ], "title": "rbd: eliminate a race in lock_dwork draining on unmap", "x_generator": { "engine": "bippy-1.2.0" } } } }