{"id":"CVE-2026-43271","state":"PUBLISHED","title":"md-cluster: fix NULL pointer dereference in process_metadata_update","description":"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_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.","publishedAt":"2026-05-06T11:28:55.507Z","updatedAt":"2026-10-30T12:25:21.976Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"b65ea893290056bee380d0c8eeb47797c2bcb311","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"dec123825c1ed74d98fd5fc7571a851dea4f46ff","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"721599e837d3f4c0e6cc14da059612c017b6d3ec","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"dceb5a843910004cb118148e267036104fc3ee43","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"f150e753cb8dd756085f46e86f2c35ce472e0a3c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/md-cluster.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.128","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","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-cluster.c"]}],"references":["https://git.kernel.org/stable/c/b65ea893290056bee380d0c8eeb47797c2bcb311","https://git.kernel.org/stable/c/a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1","https://git.kernel.org/stable/c/dec123825c1ed74d98fd5fc7571a851dea4f46ff","https://git.kernel.org/stable/c/721599e837d3f4c0e6cc14da059612c017b6d3ec","https://git.kernel.org/stable/c/dceb5a843910004cb118148e267036104fc3ee43","https://git.kernel.org/stable/c/f150e753cb8dd756085f46e86f2c35ce472e0a3c"],"weaknesses":[],"ingestedAt":"2026-10-30T12:42:04.495Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43271.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43271","state":"PUBLISHED","datePublished":"2026-05-06T11:28:55.507Z","dateUpdated":"2026-10-30T12:25:21.976Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:55.998Z"},"containers":{"cna":{"title":"md-cluster: fix NULL pointer dereference in process_metadata_update","descriptions":[{"lang":"en","value":"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_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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"b65ea893290056bee380d0c8eeb47797c2bcb311","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"a61c1bc84c4a0f1e7c2fe55b0f43d7d94af4adf1","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"dec123825c1ed74d98fd5fc7571a851dea4f46ff","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"721599e837d3f4c0e6cc14da059612c017b6d3ec","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"dceb5a843910004cb118148e267036104fc3ee43","versionType":"git"},{"version":"0ba959774e93911caff596de6391f085fb640ac4","status":"affected","lessThan":"f150e753cb8dd756085f46e86f2c35ce472e0a3c","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/md/md-cluster.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.12","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.128","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","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-cluster.c"]}],"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"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:25:21.976Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.6.128"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.12.75"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.18.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.19.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}