{"id":"CVE-2026-43271","title":"md-cluster: fix NULL pointer dereference in process_metadata_update","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nmd-cluster: fix NULL pointer dereference in process_metadata_update\n\nThe function process_metadata_update() blindly dereferences the 'thread'\npointer (acquired via rcu_…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < b65ea893290056bee380d0c8eeb47797c2bcb311","Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1","Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < dec123825c1ed74d98fd5fc7571a851dea4f46ff","Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < 721599e837d3f4c0e6cc14da059612c017b6d3ec","Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < dceb5a843910004cb118148e267036104fc3ee43","Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < f150e753cb8dd756085f46e86f2c35ce472e0a3c","Linux 4.12"],"published":"2026-05-06","updated":"2026-10-30","sourceUpdated":"2026-10-30T12:25:21.976Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-43271","references":[{"url":"https://git.kernel.org/stable/c/b65ea893290056bee380d0c8eeb47797c2bcb311"},{"url":"https://git.kernel.org/stable/c/a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1"},{"url":"https://git.kernel.org/stable/c/dec123825c1ed74d98fd5fc7571a851dea4f46ff"},{"url":"https://git.kernel.org/stable/c/721599e837d3f4c0e6cc14da059612c017b6d3ec"},{"url":"https://git.kernel.org/stable/c/dceb5a843910004cb118148e267036104fc3ee43"},{"url":"https://git.kernel.org/stable/c/f150e753cb8dd756085f46e86f2c35ce472e0a3c"}],"tags":["cve.org"],"epss":0.00117,"epssPercentile":0.01652,"ingestedAt":"2026-11-05T15:02:32.283Z","slug":"CVE-2026-43271","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nmd-cluster: fix NULL pointer dereference in process_metadata_update\n\nThe function process_metadata_update() blindly dereferences the 'thread'\npointer (acquired via rcu_dereference_protected) within the wait_event()\nmacro.\n\nWhile the code comment states \"daemon thread must exist\", there is a valid\nrace condition window during the MD array startup sequence (md_run):\n\n1. bitmap_load() is called, which invokes md_cluster_ops->join().\n2. join() starts the \"cluster_recv\" thread (recv_daemon).\n3. At this point, recv_daemon is active and processing messages.\n4. However, mddev->thread (the main MD thread) is not initialized until\n   later in md_run().\n\nIf a METADATA_UPDATED message is received from a remote node during this\nspecific window, process_metadata_update() will be called while\nmddev->thread is still NULL, leading to a kernel panic.\n\nTo fix this, we must validate the 'thread' pointer. If it is NULL, we\nrelease the held lock (no_new_dev_lockres) and return early, safely\nignoring the update request as the array is not yet fully ready to\nprocess it.\n\n## Affected\n\n- `Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < b65ea893290056bee380d0c8eeb47797c2bcb311`\n- `Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1`\n- `Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < dec123825c1ed74d98fd5fc7571a851dea4f46ff`\n- `Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < 721599e837d3f4c0e6cc14da059612c017b6d3ec`\n- `Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < dceb5a843910004cb118148e267036104fc3ee43`\n- `Linux >= 0ba959774e93911caff596de6391f085fb640ac4 < f150e753cb8dd756085f46e86f2c35ce472e0a3c`\n- `Linux 4.12`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}