{"id":"CVE-2026-45955","state":"PUBLISHED","title":"md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmd/md-llbitmap: fix percpu_ref not resurrected on suspend timeout\n\nWhen llbitmap_suspend_timeout() times out waiting for percpu_ref to\nbecome zero, it returns -ETIMEDOUT without resurrecting the percpu_ref.\nThe caller (md_llbitmap_daemon_fn) then continues to the next page\nwithout calling llbitmap_resume(), leaving the percpu_ref in a killed\nstate permanently.\n\nFix this by resurrecting the percpu_ref before returning the error,\nensuring the page control structure remains usable for subsequent\noperations.","publishedAt":"2026-05-27T12:18:10.951Z","updatedAt":"2026-10-19T19:26:40.445Z","severity":{"score":7.1,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5ab829f1971dc99f2aac10846c378e67fc875abc","status":"affected","lessThan":"095417d6b669c2dec39a5842ccb94df915f97f54","versionType":"git"},{"version":"5ab829f1971dc99f2aac10846c378e67fc875abc","status":"affected","lessThan":"2446d099350185caeed19ab2c0270451a97296fb","versionType":"git"},{"version":"5ab829f1971dc99f2aac10846c378e67fc875abc","status":"affected","lessThan":"d119bd2e1643cc023210ff3c6f0657e4f914e71d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/md-llbitmap.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.18","versionType":"semver"},{"version":"6.18.14","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.4","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/md-llbitmap.c"]}],"references":["https://git.kernel.org/stable/c/095417d6b669c2dec39a5842ccb94df915f97f54","https://git.kernel.org/stable/c/2446d099350185caeed19ab2c0270451a97296fb","https://git.kernel.org/stable/c/d119bd2e1643cc023210ff3c6f0657e4f914e71d"],"weaknesses":["CWE-404"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/45xxx/CVE-2026-45955.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-45955","state":"PUBLISHED","datePublished":"2026-05-27T12:18:10.951Z","dateUpdated":"2026-10-19T19:26:40.445Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-13T15:03:33.088Z"},"containers":{"cna":{"title":"md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmd/md-llbitmap: fix percpu_ref not resurrected on suspend timeout\n\nWhen llbitmap_suspend_timeout() times out waiting for percpu_ref to\nbecome zero, it returns -ETIMEDOUT without resurrecting the percpu_ref.\nThe caller (md_llbitmap_daemon_fn) then continues to the next page\nwithout calling llbitmap_resume(), leaving the percpu_ref in a killed\nstate permanently.\n\nFix this by resurrecting the percpu_ref before returning the error,\nensuring the page control structure remains usable for subsequent\noperations."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5ab829f1971dc99f2aac10846c378e67fc875abc","status":"affected","lessThan":"095417d6b669c2dec39a5842ccb94df915f97f54","versionType":"git"},{"version":"5ab829f1971dc99f2aac10846c378e67fc875abc","status":"affected","lessThan":"2446d099350185caeed19ab2c0270451a97296fb","versionType":"git"},{"version":"5ab829f1971dc99f2aac10846c378e67fc875abc","status":"affected","lessThan":"d119bd2e1643cc023210ff3c6f0657e4f914e71d","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/md-llbitmap.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.18","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.18","versionType":"semver"},{"version":"6.18.14","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.4","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/md-llbitmap.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/095417d6b669c2dec39a5842ccb94df915f97f54"},{"url":"https://git.kernel.org/stable/c/2446d099350185caeed19ab2c0270451a97296fb"},{"url":"https://git.kernel.org/stable/c/d119bd2e1643cc023210ff3c6f0657e4f914e71d"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H","baseScore":7.1,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The flaw is in the MD lockless bitmap (`md-llbitmap`), reached only from the block/MD write path (`md_bitmap_start` → `llbitmap_start_write`), not from a network protocol handler. Any remote party must already cause writes through local VFS/block access (e.g., a file on an md-backed volume).\nAC:L - On a system with llbitmap enabled, an attacker can reliably force the timeout by racing the periodic daemon against many concurrent writes to the same bitmap page that hold `percpu_ref` until `daemon_sleep` expires; both sides of the race are attacker-driven I/O patterns.\nPR:L - Exploitation does not require real root in the init namespace: any principal that can issue writes to storage backed by an affected md array (typical unprivileged user on a multi-tenant NAS, or a member of the `disk` group with raw `/dev/md*` access) reaches the vulnerable code.\nUI:N - Triggering the race requires only sustained automated write I/O; no victim click, mount dialog, or other interactive action is needed beyond normal storage use.\nS:U - Impact stays within kernel/MD RAID scope (hang and bitmap inconsistency on the host); it does not cross a VM, container, or IOMMU security boundary.\nC:N - This is a refcount lifecycle logic bug, not memory corruption; there is no out-of-bounds access, UAF, or other primitive that discloses kernel memory.\nI:H - After the bug, `llbitmap_raise_barrier()` can block new writes before `llbitmap_state_machine()` runs, so dirty regions may not be recorded; combined with uncleared dirty bits on other paths, RAID resync decisions can be wrong after crash—high integrity risk for redundant storage.\nA:H - A permanently killed `percpu_ref` leaves writers stuck in uninterruptible `wait_event` in `llbitmap_raise_barrier()`, causing indefinite write hangs (effective DoS) for affected bitmap pages on production NAS/RAID systems."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:28:54.212Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"6.18.14"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"6.19.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.18","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-45955","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:18:35.481520Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-404","lang":"en","type":"CWE","description":"CWE-404 Improper Resource Shutdown or Release"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:26:40.445Z"}}]}}}